diff --git a/pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/operations.dart b/pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/operations.dart
index 1d7790c69e8..b78c49f8563 100644
--- a/pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/operations.dart
+++ b/pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/operations.dart
@@ -26,12 +26,14 @@ class InvocationImpl extends Invocation {
         namedArguments = _namedArgsToSymbols(namedArguments),
         typeArguments = typeArguments == null
             ? const []
-            : typeArguments.map(wrapType).toList();
+            : new List.unmodifiable(typeArguments.map(wrapType));
 
   static Map<Symbol, dynamic> _namedArgsToSymbols(namedArgs) {
-    if (namedArgs == null) return {};
-    return new Map.fromIterable(getOwnPropertyNames(namedArgs),
-        key: _dartSymbol, value: (k) => JS('', '#[#]', namedArgs, k));
+    if (namedArgs == null) return const {};
+    return new Map.unmodifiable(new Map.fromIterable(
+        getOwnPropertyNames(namedArgs),
+        key: _dartSymbol,
+        value: (k) => JS('', '#[#]', namedArgs, k)));
   }
 }
 
@@ -206,7 +208,7 @@ _toDisplayName(name) => JS('', '''(() => {
       // Names starting with _ are escaped names used to disambiguate Dart and
       // JS names.
       if ($name[0] === '_') {
-        // Inverse of 
+        // Inverse of
         switch($name) {
           case '_get':
             return '[]';
@@ -293,7 +295,7 @@ _checkAndCall(f, ftype, obj, typeArgs, args, name) => JS('', '''(() => {
   // Apply type arguments
   if ($ftype instanceof $GenericFunctionType) {
     let formalCount = $ftype.formalCount;
-    
+
     if ($typeArgs == null) {
       $typeArgs = $ftype.instantiateDefaultBounds();
     } else if ($typeArgs.length != formalCount) {
diff --git a/pkg/dev_compiler/tool/input_sdk/private/js_array.dart b/pkg/dev_compiler/tool/input_sdk/private/js_array.dart
index 714ad2a08f2..69c90ff0f0d 100644
--- a/pkg/dev_compiler/tool/input_sdk/private/js_array.dart
+++ b/pkg/dev_compiler/tool/input_sdk/private/js_array.dart
@@ -598,17 +598,10 @@ class JSArray<E> implements List<E>, JSIndexable<E> {
   Type get runtimeType =>
       dart.wrapType(JS('', '#(#)', dart.getGenericClass(List), E));
 
-  Iterable<E> followedBy(Iterable<E> other) sync* {
-    yield* this;
-    yield* other;
-  }
+  Iterable<E> followedBy(Iterable<E> other) =>
+      new FollowedByIterable<E>.firstEfficient(this, other);
 
-  Iterable<T> whereType<T>() sync* {
-    for (var i = 0; i < this.length; i++) {
-      var element = this[i];
-      if (element is T) yield element;
-    }
-  }
+  Iterable<T> whereType<T>() => new WhereTypeIterable<T>(this);
 
   List<E> operator +(List<E> other) {
     int totalLength = this.length + other.length;
diff --git a/pkg/vm/testcases/transformations/type_flow/transformer/bench_vector.dart.expect b/pkg/vm/testcases/transformations/type_flow/transformer/bench_vector.dart.expect
index aa44be514f3..b23ebd2e5e0 100644
--- a/pkg/vm/testcases/transformations/type_flow/transformer/bench_vector.dart.expect
+++ b/pkg/vm/testcases/transformations/type_flow/transformer/bench_vector.dart.expect
@@ -20,7 +20,7 @@ class _Vector extends core::Object {
   }
   operator *([@vm.inferred-type.metadata=#lib::_Vector] self::_Vector a) → core::double {
     core::double result = 0.0;
-    for (core::int i = 0; [@vm.direct-call.metadata=dart.core::_IntegerImplementation::<??] i.{core::num::<}([@vm.direct-call.metadata=#lib::_Vector::_length] [@vm.inferred-type.metadata=!] this.{self::_Vector::_length}); i = i.{core::num::+}(1))
+    for (core::int i = 0; i.{core::num::<}([@vm.direct-call.metadata=#lib::_Vector::_length] [@vm.inferred-type.metadata=!] this.{self::_Vector::_length}); i = i.{core::num::+}(1))
       result = [@vm.direct-call.metadata=dart.core::_Double::+??] [@vm.inferred-type.metadata=dart.core::_Double] result.{core::double::+}([@vm.direct-call.metadata=dart.core::_Double::*] [@vm.inferred-type.metadata=dart.core::_Double] [@vm.direct-call.metadata=#lib::_Vector::[]] [@vm.inferred-type.metadata=dart.core::_Double] this.{self::_Vector::[]}(i).{core::double::*}([@vm.direct-call.metadata=#lib::_Vector::[]] [@vm.inferred-type.metadata=dart.core::_Double] a.{self::_Vector::[]}(i)));
     return result;
   }
@@ -29,7 +29,7 @@ class _Vector extends core::Object {
 [@vm.inferred-type.metadata=dart.core::_Double]static field core::double x = 0.0;
 static method main(core::List<core::String> args) → dynamic {
   core::Stopwatch timer = let final core::Stopwatch #t1 = new core::Stopwatch::•() in let final dynamic #t2 = [@vm.direct-call.metadata=dart.core::Stopwatch::start] #t1.{core::Stopwatch::start}() in #t1;
-  for (core::int i = 0; [@vm.direct-call.metadata=dart.core::_IntegerImplementation::<??] i.{core::num::<}(100000000); i = i.{core::num::+}(1)) {
+  for (core::int i = 0; i.{core::num::<}(100000000); i = i.{core::num::+}(1)) {
     self::x = [@vm.direct-call.metadata=dart.core::_Double::+] [@vm.inferred-type.metadata=dart.core::_Double] [@vm.inferred-type.metadata=dart.core::_Double] self::x.{core::double::+}([@vm.direct-call.metadata=#lib::_Vector::*] [@vm.inferred-type.metadata=dart.core::_Double] [@vm.inferred-type.metadata=#lib::_Vector] self::v.{self::_Vector::*}([@vm.inferred-type.metadata=#lib::_Vector] self::v));
   }
   [@vm.direct-call.metadata=dart.core::Stopwatch::stop] timer.{core::Stopwatch::stop}();
diff --git a/runtime/lib/array_patch.dart b/runtime/lib/array_patch.dart
index 820594a2216..27fc74574f3 100644
--- a/runtime/lib/array_patch.dart
+++ b/runtime/lib/array_patch.dart
@@ -8,6 +8,9 @@
 // whether a parameter was passed.
 class _GrowableArrayMarker implements int {
   const _GrowableArrayMarker();
+  noSuchMethod(_) {
+    throw new UnimplementedError();
+  }
 }
 
 const _GROWABLE_ARRAY_MARKER = const _GrowableArrayMarker();
diff --git a/runtime/lib/bigint.dart b/runtime/lib/bigint.dart
index 03a4b7029f8..b6a9db372a9 100644
--- a/runtime/lib/bigint.dart
+++ b/runtime/lib/bigint.dart
@@ -1863,7 +1863,7 @@ class _Bigint extends _IntegerImplementation {
 }
 
 // Interface for modular reduction.
-class _Reduction {
+abstract class _Reduction {
   // Return the number of digits used by r_digits.
   int _convert(_Bigint x, Uint32List r_digits);
   int _mul(Uint32List x_digits, int x_used, Uint32List y_digits, int y_used,
diff --git a/runtime/lib/immutable_map.dart b/runtime/lib/immutable_map.dart
index 726a376f7ea..0417d71218d 100644
--- a/runtime/lib/immutable_map.dart
+++ b/runtime/lib/immutable_map.dart
@@ -5,12 +5,21 @@
 // part of "core_patch.dart";
 
 /// Immutable map class for compiler generated map literals.
+// TODO(lrn): Extend MapBase with UnmodifiableMapMixin when mixins
+// support forwarding const constructors.
 class _ImmutableMap<K, V> implements Map<K, V> {
   final _ImmutableList _kvPairs;
 
   const _ImmutableMap._create(_ImmutableList keyValuePairs)
       : _kvPairs = keyValuePairs;
 
+  Map<K2, V2> cast<K2, V2>() {
+    Map<Object, Object> self = this;
+    return (self is Map<K2, V2>) ? self : this.retype<K2, V2>();
+  }
+
+  Map<K2, V2> retype<K2, V2>() => Map.castFrom<K, V, K2, V2>(this);
+
   V operator [](Object key) {
     // To preserve the key-value order of the map literal, the keys are
     // not sorted. Need to do linear search or implement an additional
@@ -69,6 +78,10 @@ class _ImmutableMap<K, V> implements Map<K, V> {
     throw new UnsupportedError("Cannot set value in unmodifiable Map");
   }
 
+  void addAll(Map<K, V> other) {
+    throw new UnsupportedError("Cannot set value in unmodifiable Map");
+  }
+
   V putIfAbsent(K key, V ifAbsent()) {
     throw new UnsupportedError("Cannot set value in unmodifiable Map");
   }
diff --git a/runtime/lib/typed_data_patch.dart b/runtime/lib/typed_data_patch.dart
index 5e2312c4229..4d6161c75e4 100644
--- a/runtime/lib/typed_data_patch.dart
+++ b/runtime/lib/typed_data_patch.dart
@@ -12,6 +12,7 @@ import "dart:_internal"
         ClassID,
         CodeUnits,
         ExpandIterable,
+        FollowedByIterable,
         IterableElementError,
         ListMapView,
         Lists,
@@ -23,6 +24,7 @@ import "dart:_internal"
         SubListIterable,
         TakeWhileIterable,
         WhereIterable,
+        WhereTypeIterable,
         patch;
 
 import "dart:collection" show ListBase;
@@ -112,6 +114,11 @@ abstract class _IntListMixin implements List<int> {
 
   List<int> _createList(int length);
 
+  Iterable<T> whereType<T>() => new WhereTypeIterable<T>(this);
+
+  Iterable<int> followedBy(Iterable<int> other) =>
+      new FollowedByIterable<int>.firstEfficient(this, other);
+
   List<R> cast<R>() {
     List<Object> self = this;
     return self is List<R> ? self : List.castFrom<int, R>(this);
@@ -466,6 +473,11 @@ abstract class _DoubleListMixin implements List<double> {
 
   List<double> _createList(int length);
 
+  Iterable<T> whereType<T>() => new WhereTypeIterable<T>(this);
+
+  Iterable<double> followedBy(Iterable<double> other) =>
+      new FollowedByIterable<double>.firstEfficient(this, other);
+
   List<R> cast<R>() {
     List<Object> self = this;
     return self is List<R> ? self : List.castFrom<double, R>(this);
@@ -823,6 +835,11 @@ abstract class _Float32x4ListMixin implements List<Float32x4> {
 
   List<Float32x4> _createList(int length);
 
+  Iterable<T> whereType<T>() => new WhereTypeIterable<T>(this);
+
+  Iterable<Float32x4> followedBy(Iterable<Float32x4> other) =>
+      new FollowedByIterable<Float32x4>.firstEfficient(this, other);
+
   List<R> cast<R>() {
     List<Object> self = this;
     return self is List<R> ? self : List.castFrom<Float32x4, R>(this);
@@ -1184,6 +1201,11 @@ abstract class _Int32x4ListMixin implements List<Int32x4> {
 
   List<Int32x4> _createList(int length);
 
+  Iterable<T> whereType<T>() => new WhereTypeIterable<T>(this);
+
+  Iterable<Int32x4> followedBy(Iterable<Int32x4> other) =>
+      new FollowedByIterable<Int32x4>.firstEfficient(this, other);
+
   List<R> cast<R>() {
     List<Object> self = this;
     return self is List<R> ? self : List.castFrom<Int32x4, R>(this);
@@ -1544,6 +1566,11 @@ abstract class _Float64x2ListMixin implements List<Float64x2> {
 
   List<Float64x2> _createList(int length);
 
+  Iterable<T> whereType<T>() => new WhereTypeIterable<T>(this);
+
+  Iterable<Float64x2> followedBy(Iterable<Float64x2> other) =>
+      new FollowedByIterable<Float64x2>.firstEfficient(this, other);
+
   List<R> cast<R>() {
     List<Object> self = this;
     return self is List<R> ? self : List.castFrom<Float64x2, R>(this);
diff --git a/sdk/lib/_internal/js_runtime/lib/js_array.dart b/sdk/lib/_internal/js_runtime/lib/js_array.dart
index e8dbab75942..563297a03db 100644
--- a/sdk/lib/_internal/js_runtime/lib/js_array.dart
+++ b/sdk/lib/_internal/js_runtime/lib/js_array.dart
@@ -635,17 +635,10 @@ class JSArray<E> extends Interceptor implements List<E>, JSIndexable {
     return new ListMapView<E>(this);
   }
 
-  Iterable<E> followedBy(Iterable<E> other) sync* {
-    yield* this;
-    yield* other;
-  }
+  Iterable<E> followedBy(Iterable<E> other) =>
+      new FollowedByIterable<E>.firstEfficient(this, other);
 
-  Iterable<T> whereType<T>() sync* {
-    for (var i = 0; i < this.length; i++) {
-      var element = this[i];
-      if (element is T) yield element;
-    }
-  }
+  Iterable<T> whereType<T>() => new WhereTypeIterable<T>(this);
 
   List<E> operator +(List<E> other) {
     int totalLength = this.length + other.length;
diff --git a/sdk/lib/collection/iterable.dart b/sdk/lib/collection/iterable.dart
index 7d028a4d88d..67bfdd8b836 100644
--- a/sdk/lib/collection/iterable.dart
+++ b/sdk/lib/collection/iterable.dart
@@ -26,18 +26,19 @@ abstract class IterableMixin<E> implements Iterable<E> {
 
   Iterable<E> where(bool f(E element)) => new WhereIterable<E>(this, f);
 
-  Iterable<T> whereType<T>() sync* {
-    for (Object element in this) if (element is T) yield element;
-  }
+  Iterable<T> whereType<T>() => new WhereTypeIterable<T>(this);
 
   Iterable<T> expand<T>(Iterable<T> f(E element)) =>
       new ExpandIterable<E, T>(this, f);
 
-  Iterable<E> followedBy(Iterable<E> other) sync* {
-    // TODO(lrn): Optimize this (some operations can be more efficient,
-    // and the concatenation has efficient length if the source iterables do).
-    yield* this;
-    yield* other;
+  Iterable<E> followedBy(Iterable<E> other) {
+    // Type workaround because IterableMixin<E> doesn't promote
+    // to EfficientLengthIterable<E>.
+    Iterable<E> self = this;
+    if (self is EfficientLengthIterable<E>) {
+      return new FollowedByIterable<E>.firstEfficient(self, other);
+    }
+    return new FollowedByIterable<E>(this, other);
   }
 
   bool contains(Object element) {
diff --git a/sdk/lib/collection/list.dart b/sdk/lib/collection/list.dart
index 57e5ef4c4fb..2a5792dbfa8 100644
--- a/sdk/lib/collection/list.dart
+++ b/sdk/lib/collection/list.dart
@@ -59,12 +59,8 @@ abstract class ListMixin<E> implements List<E> {
 
   E elementAt(int index) => this[index];
 
-  Iterable<E> followedBy(Iterable<E> other) sync* {
-    for (var i = 0; i < length; i++) {
-      yield this[i];
-    }
-    yield* other;
-  }
+  Iterable<E> followedBy(Iterable<E> other) =>
+      new FollowedByIterable<E>.firstEfficient(this, other);
 
   void forEach(void action(E element)) {
     int length = this.length;
@@ -195,9 +191,7 @@ abstract class ListMixin<E> implements List<E> {
 
   Iterable<E> where(bool test(E element)) => new WhereIterable<E>(this, test);
 
-  Iterable<T> whereType<T>() sync* {
-    for (var element in this) if (element is T) yield (element as T);
-  }
+  Iterable<T> whereType<T>() => new WhereTypeIterable<T>(this);
 
   Iterable<T> map<T>(T f(E element)) => new MappedListIterable<E, T>(this, f);
 
diff --git a/sdk/lib/collection/set.dart b/sdk/lib/collection/set.dart
index 5d51dffe04a..71bf718fd7a 100644
--- a/sdk/lib/collection/set.dart
+++ b/sdk/lib/collection/set.dart
@@ -58,16 +58,10 @@ abstract class SetMixin<E> implements Set<E> {
 
   Set<R> retype<R>() => Set.castFrom<E, R>(this);
 
-  Iterable<E> followedBy(Iterable<E> other) sync* {
-    // TODO(lrn): Optimize this (some operations can be more efficient,
-    // and the concatenation has efficient length if the source iterables do).
-    yield* this;
-    yield* other;
-  }
+  Iterable<E> followedBy(Iterable<E> other) =>
+      new FollowedByIterable<E>.firstEfficient(this, other);
 
-  Iterable<T> whereType<T>() sync* {
-    for (Object element in this) if (element is T) yield element;
-  }
+  Iterable<T> whereType<T>() => new WhereTypeIterable<T>(this);
 
   void clear() {
     removeAll(toList());
diff --git a/sdk/lib/core/iterable.dart b/sdk/lib/core/iterable.dart
index d3cc85b52dd..410b57d8dcd 100644
--- a/sdk/lib/core/iterable.dart
+++ b/sdk/lib/core/iterable.dart
@@ -186,11 +186,11 @@ abstract class Iterable<E> {
    * and, after that, the elements of [other], in the same order as in the
    * original iterables.
    */
-  Iterable<E> followedBy(Iterable<E> other) sync* {
-    // TODO(lrn): Optimize this (some operations can be more efficient,
-    // and the concatenation has efficient length if the source iterables do).
-    yield* this;
-    yield* other;
+  Iterable<E> followedBy(Iterable<E> other) {
+    if (this is EfficientLengthIterable<E>) {
+      return new FollowedByIterable<E>.firstEfficient(this, other);
+    }
+    return new FollowedByIterable<E>(this, other);
   }
 
   /**
@@ -236,9 +236,7 @@ abstract class Iterable<E> {
    * the returned [Iterable] may yield different results,
    * if the underlying elements change between iterations.
    */
-  Iterable<T> whereType<T>() sync* {
-    for (var element in this) if (element is T) yield (element as T);
-  }
+  Iterable<T> whereType<T>() => new WhereTypeIterable<T>(this);
 
   /**
    * Expands each element of this [Iterable] into zero or more elements.
diff --git a/sdk/lib/internal/iterable.dart b/sdk/lib/internal/iterable.dart
index d8941c9f2bb..1c11e53caa7 100644
--- a/sdk/lib/internal/iterable.dart
+++ b/sdk/lib/internal/iterable.dart
@@ -767,6 +767,125 @@ class EmptyIterator<E> implements Iterator<E> {
   E get current => null;
 }
 
+class FollowedByIterable<E> extends Iterable<E> {
+  final Iterable<E> _first;
+  final Iterable<E> _second;
+  FollowedByIterable(this._first, this._second);
+
+  factory FollowedByIterable.firstEfficient(
+      EfficientLengthIterable<E> first, Iterable<E> second) {
+    if (second is EfficientLengthIterable<E>) {
+      return new EfficientLengthFollowedByIterable<E>(first, second);
+    }
+    return new FollowedByIterable<E>(first, second);
+  }
+
+  Iterator<E> get iterator => new FollowedByIterator(_first, _second);
+
+  int get length => _first.length + _second.length;
+  bool get isEmpty => _first.isEmpty && _second.isEmpty;
+  bool get isNotEmpty => _first.isNotEmpty || _second.isNotEmpty;
+
+  // May be more efficient if either iterable is a Set.
+  bool contains(Object value) =>
+      _first.contains(value) || _second.contains(value);
+
+  E get first {
+    var iterator = _first.iterator;
+    if (iterator.moveNext()) return iterator.current;
+    return _second.first;
+  }
+
+  E get last {
+    var iterator = _second.iterator;
+    if (iterator.moveNext()) {
+      E last = iterator.current;
+      while (iterator.moveNext()) last = iterator.current;
+      return last;
+    }
+    return _first.last;
+  }
+
+  // If linear sequences of `followedBy` becomes an issue, we can flatten
+  // into a list of iterables instead of a tree or spine.
+}
+
+class EfficientLengthFollowedByIterable<E> extends FollowedByIterable<E>
+    implements EfficientLengthIterable<E> {
+  EfficientLengthFollowedByIterable(
+      EfficientLengthIterable<E> first, EfficientLengthIterable<E> second)
+      : super(first, second);
+
+  Iterable<E> skip(int count) {
+    int firstLength = _first.length;
+    if (count >= firstLength) return _second.skip(count - firstLength);
+    return new EfficientLengthFollowedByIterable<E>(
+        _first.skip(count), _second);
+  }
+
+  Iterable<E> take(int count) {
+    int firstLength = _first.length;
+    if (count <= firstLength) return _first.take(count);
+    return new EfficientLengthFollowedByIterable<E>(
+        _first, _second.take(count - firstLength));
+  }
+
+  E elementAt(int index) {
+    int firstLength = _first.length;
+    if (index < firstLength) return _first.elementAt(index);
+    return _second.elementAt(index - firstLength);
+  }
+
+  E get first {
+    if (_first.isNotEmpty) return _first.first;
+    return _second.first;
+  }
+
+  E get last {
+    if (_second.isNotEmpty) return _second.last;
+    return _first.last;
+  }
+}
+
+class FollowedByIterator<E> implements Iterator<E> {
+  Iterator<E> _currentIterator;
+  Iterable<E> _nextIterable;
+
+  FollowedByIterator(Iterable<E> first, this._nextIterable)
+      : _currentIterator = first.iterator;
+
+  bool moveNext() {
+    if (_currentIterator.moveNext()) return true;
+    if (_nextIterable != null) {
+      _currentIterator = _nextIterable.iterator;
+      _nextIterable = null;
+      return _currentIterator.moveNext();
+    }
+    return false;
+  }
+
+  E get current => _currentIterator.current;
+}
+
+class WhereTypeIterable<T> extends Iterable<T> {
+  final Iterable<Object> _source;
+  WhereTypeIterable(this._source);
+  Iterator<T> get iterator => new WhereTypeIterator<T>(_source.iterator);
+}
+
+class WhereTypeIterator<T> implements Iterator<T> {
+  final Iterator<Object> _source;
+  WhereTypeIterator(this._source);
+  bool moveNext() {
+    while (_source.moveNext()) {
+      if (_source.current is T) return true;
+    }
+    return false;
+  }
+
+  T get current => _source.current;
+}
+
 /**
  * Creates errors throw by [Iterable] when the element count is wrong.
  */
diff --git a/tests/compiler/dart2js/old_frontend/analyze_api_test.dart b/tests/compiler/dart2js/old_frontend/analyze_api_test.dart
index c74aee2273b..458824ef121 100644
--- a/tests/compiler/dart2js/old_frontend/analyze_api_test.dart
+++ b/tests/compiler/dart2js/old_frontend/analyze_api_test.dart
@@ -18,25 +18,7 @@ import 'package:async_helper/async_helper.dart';
  * the error/warning message in the list of white-listings for each file.
  */
 // TODO(johnniwinther): Support canonical URIs as keys.
-const Map<String, List<String>> WHITE_LIST = const {
-  "sdk/lib/_internal/js_runtime/lib/js_array.dart": const [
-    "Method type variables do not have a runtime value.",
-  ],
-  "sdk/lib/collection/iterable.dart": const [
-    "Method type variables do not have a runtime value.",
-  ],
-  "sdk/lib/collection/list.dart": const [
-    "Method type variables do not have a runtime value.",
-    "Method type variables are treated as `dynamic` in `as` expressions.",
-  ],
-  "sdk/lib/collection/set.dart": const [
-    "Method type variables do not have a runtime value.",
-  ],
-  "sdk/lib/core/iterable.dart": const [
-    "Method type variables do not have a runtime value.",
-    "Method type variables are treated as `dynamic` in `as` expressions.",
-  ],
-};
+const Map<String, List<String>> WHITE_LIST = const {};
 
 void main() {
   var uriList = new List<Uri>();
diff --git a/tests/compiler/dart2js/old_frontend/diagnose_ambiguous_test.dart b/tests/compiler/dart2js/old_frontend/diagnose_ambiguous_test.dart
index 8af9a960d57..53538ed95f1 100644
--- a/tests/compiler/dart2js/old_frontend/diagnose_ambiguous_test.dart
+++ b/tests/compiler/dart2js/old_frontend/diagnose_ambiguous_test.dart
@@ -28,12 +28,6 @@ void main() {
           "memory:library.dart:41:47:'hest' is defined here.:info",
       "MessageKind.DUPLICATE_IMPORT:"
           "memory:main.dart:86:92:Duplicate import of 'hest'.:warning",
-      "MessageKind.HIDDEN_WARNINGS:"
-          "null:null:null:1 warning(s) suppressed in dart:_interceptors.:hint",
-      "MessageKind.HIDDEN_WARNINGS_HINTS:"
-          "null:null:null:1 warning(s) and 1 hint(s) suppressed in dart:core.:hint",
-      "MessageKind.HIDDEN_WARNINGS_HINTS:"
-          "null:null:null:3 warning(s) and 1 hint(s) suppressed in dart:collection.:hint",
       "MessageKind.IMPORTED_HERE:"
           "memory:main.dart:0:22:'hest' is imported here.:info",
       "MessageKind.IMPORTED_HERE:"
diff --git a/tests/compiler/dart2js/old_frontend/duplicate_library_test.dart b/tests/compiler/dart2js/old_frontend/duplicate_library_test.dart
index 44c81c897e6..0f10f25f398 100644
--- a/tests/compiler/dart2js/old_frontend/duplicate_library_test.dart
+++ b/tests/compiler/dart2js/old_frontend/duplicate_library_test.dart
@@ -14,7 +14,7 @@ import '../memory_compiler.dart';
 
 void check(String kind, Iterable<CollectedMessage> messages,
     List<MessageKind> expectedMessageKinds) {
-  Expect.equals(messages.length, expectedMessageKinds.length,
+  Expect.equals(expectedMessageKinds.length, messages.length,
       "Unexpected $kind count: $messages");
   int i = 0;
   messages.forEach((CollectedMessage message) {
@@ -56,11 +56,7 @@ library lib.foo;
 """
   }, warnings: [
     MessageKind.DUPLICATED_LIBRARY_RESOURCE
-  ], hints: [
-    MessageKind.HIDDEN_WARNINGS,
-    MessageKind.HIDDEN_WARNINGS_HINTS,
-    MessageKind.HIDDEN_WARNINGS_HINTS,
-  ]);
+  ], hints: []);
 
   await test({
     'main.dart': """
@@ -79,11 +75,7 @@ library lib.bar;
 """
   }, warnings: [
     MessageKind.DUPLICATED_LIBRARY_RESOURCE
-  ], hints: [
-    MessageKind.HIDDEN_WARNINGS,
-    MessageKind.HIDDEN_WARNINGS_HINTS,
-    MessageKind.HIDDEN_WARNINGS_HINTS,
-  ]);
+  ], hints: []);
 
   await test({
     'main.dart': """
@@ -102,11 +94,7 @@ library lib.baz;
 """
   }, warnings: [
     MessageKind.DUPLICATED_LIBRARY_RESOURCE
-  ], hints: [
-    MessageKind.HIDDEN_WARNINGS,
-    MessageKind.HIDDEN_WARNINGS_HINTS,
-    MessageKind.HIDDEN_WARNINGS_HINTS,
-  ]);
+  ], hints: []);
 
   await test({
     'main.dart': """
@@ -130,11 +118,7 @@ library lib.boz;
 """
   }, warnings: [
     MessageKind.DUPLICATED_LIBRARY_RESOURCE
-  ], hints: [
-    MessageKind.HIDDEN_WARNINGS,
-    MessageKind.HIDDEN_WARNINGS_HINTS,
-    MessageKind.HIDDEN_WARNINGS_HINTS,
-  ]);
+  ], hints: []);
 
   await test({
     'main.dart': """
@@ -148,9 +132,6 @@ import 'pkg/lib/qux.dart';
 """
   }, hints: [
     MessageKind.DUPLICATED_RESOURCE,
-    MessageKind.HIDDEN_WARNINGS,
-    MessageKind.HIDDEN_WARNINGS_HINTS,
-    MessageKind.HIDDEN_WARNINGS_HINTS,
   ]);
 
   await test({
@@ -169,9 +150,5 @@ library lib;
   }, warnings: [
     MessageKind.DUPLICATED_LIBRARY_NAME,
     MessageKind.DUPLICATED_LIBRARY_NAME
-  ], hints: [
-    MessageKind.HIDDEN_WARNINGS,
-    MessageKind.HIDDEN_WARNINGS_HINTS,
-    MessageKind.HIDDEN_WARNINGS_HINTS,
-  ]);
+  ], hints: []);
 }
diff --git a/tests/corelib_2/corelib_2.status b/tests/corelib_2/corelib_2.status
index e0bcaf19206..dfcae0f1c24 100644
--- a/tests/corelib_2/corelib_2.status
+++ b/tests/corelib_2/corelib_2.status
@@ -8,6 +8,9 @@ int_parse_radix_bad_handler_test: MissingCompileTimeError
 iterable_element_at_test/static: Pass
 num_sign_test: Crash, Pass # Issue 31768
 
+[ $compiler == dart2js ]
+iterable_where_type_test: RuntimeError # issue 31718
+
 [ $compiler != dartdevc ]
 error_stack_trace_test/static: MissingCompileTimeError
 
diff --git a/tests/corelib_2/iterable_followed_by_test.dart b/tests/corelib_2/iterable_followed_by_test.dart
new file mode 100644
index 00000000000..5edf0e3e223
--- /dev/null
+++ b/tests/corelib_2/iterable_followed_by_test.dart
@@ -0,0 +1,102 @@
+// Copyright (c) 2018, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import "dart:collection" show Queue;
+import "dart:typed_data" show Int32List;
+
+import "package:expect/expect.dart";
+
+// Tests behavior of result of an operation on a followedBy iterable.
+test(List expects, Iterable iterable, [String name]) {
+  try {
+    Expect.isFalse(iterable is List, "$name is! List");
+    Expect.isFalse(iterable is Set, "$name is! Set");
+    Expect.isFalse(iterable is Queue, "$name is! Queue");
+    if (expects.isNotEmpty) {
+      Expect.equals(expects.first, iterable.first, "$name: first");
+      Expect.equals(expects.last, iterable.last, "$name: last");
+    } else {
+      Expect.throwsStateError(() => iterable.first, "$name: first");
+      Expect.throwsStateError(() => iterable.last, "$name: last");
+    }
+    var it = iterable.iterator;
+    for (int index = 0; index < expects.length; index++) {
+      Expect.isTrue(it.moveNext(), "$name: has element $index");
+      var expect = expects[index];
+      Expect.equals(expect, it.current, "$name at $index");
+      Expect.equals(
+          expect, iterable.elementAt(index), "$name: elementAt($index)");
+      Expect.isTrue(iterable.contains(expect), "$name:contains $index");
+    }
+    Expect.isFalse(it.moveNext(),
+        "$name: extra element at ${expects.length}: ${it.current}");
+  } on Error {
+    print("Failed during: $name");
+    rethrow;
+  }
+}
+
+// Tests various operations on the a followedBy iterable.
+tests(List<int> expects, Iterable<int> follow, [String name]) {
+  int length = expects.length;
+  test(expects, follow, name);
+  for (int i = 0; i <= length; i++) {
+    test(expects.sublist(i), follow.skip(i), "$name.skip($i)");
+  }
+  for (int i = 0; i <= length; i++) {
+    test(expects.sublist(0, i), follow.take(i), "$name.take($i)");
+  }
+  for (int i = 0; i <= length; i++) {
+    for (int j = 0; j <= length - i; j++) {
+      test(expects.sublist(i, i + j), follow.skip(i).take(j),
+          "$name.skiptake($i,${i+j})");
+      test(expects.sublist(i, i + j), follow.take(i + j).skip(i),
+          "$name.takeskip($i,${i+j})");
+    }
+  }
+}
+
+// Tests various different types of iterables as first and second operand.
+types(List expects, List<int> first, List<int> second, [String name]) {
+  var conversions = <String, Iterable<int> Function(List<int>)>{
+    "const": toConst,
+    "list": toList,
+    "unmod": toUnmodifiable,
+    "set": toSet,
+    "queue": toQueue,
+    "eff-len-iter": toELIter,
+    "non-eff-iter": toNEIter,
+    "typed": toTyped,
+    "keys": toKeys,
+    "values": toValues,
+  };
+  conversions.forEach((n1, c1) {
+    conversions.forEach((n2, c2) {
+      tests(expects, c1(first).followedBy(c2(second)), "$name:$n1/$n2");
+    });
+  });
+}
+
+List<int> toConst(List<int> elements) => elements;
+List<int> toList(List<int> elements) => elements.toList();
+List<int> toUnmodifiable(List<int> elements) =>
+    new List<int>.unmodifiable(elements);
+Set<int> toSet(List<int> elements) => elements.toSet();
+Queue<int> toQueue(List<int> elements) => new Queue<int>.from(elements);
+// Creates an efficient-length iterable.
+Iterable<int> toELIter(List<int> elements) => elements.map<int>((x) => x);
+// Creates a non-efficient-length iterable.
+Iterable<int> toNEIter(List<int> elements) => elements.where((x) => true);
+List<int> toTyped(List<int> elements) => new Int32List.fromList(elements);
+Iterable<int> toKeys(List<int> elements) =>
+    new Map<int, int>.fromIterables(elements, elements).keys;
+Iterable<int> toValues(List<int> elements) =>
+    new Map<int, int>.fromIterables(elements, elements).values;
+
+main() {
+  types(<int>[], const <int>[], const <int>[], "0+0");
+  types(<int>[1, 2, 3, 4], const <int>[], const <int>[1, 2, 3, 4], "0+4");
+  types(<int>[1, 2, 3, 4], const <int>[1, 2], const <int>[3, 4], "2+2");
+  types(<int>[1, 2, 3, 4], const <int>[1, 2, 3, 4], const <int>[], "4+0");
+}
diff --git a/tests/corelib_2/iterable_where_type_test.dart b/tests/corelib_2/iterable_where_type_test.dart
new file mode 100644
index 00000000000..8715149f049
--- /dev/null
+++ b/tests/corelib_2/iterable_where_type_test.dart
@@ -0,0 +1,105 @@
+// Copyright (c) 2018, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import "dart:collection" show Queue;
+import "dart:typed_data" show Int32List;
+
+import "package:expect/expect.dart";
+
+// Tests behavior of result of an operation on a followedBy iterable.
+test(List expects, Iterable iterable, [String name]) {
+  try {
+    Expect.isFalse(iterable is List, "$name is! List");
+    Expect.isFalse(iterable is Set, "$name is! Set");
+    Expect.isFalse(iterable is Queue, "$name is! Queue");
+    if (expects.isNotEmpty) {
+      Expect.equals(expects.first, iterable.first, "$name: first");
+      Expect.equals(expects.last, iterable.last, "$name: last");
+    } else {
+      Expect.throwsStateError(() => iterable.first, "$name: first");
+      Expect.throwsStateError(() => iterable.last, "$name: last");
+    }
+    var it = iterable.iterator;
+    for (int index = 0; index < expects.length; index++) {
+      Expect.isTrue(it.moveNext(), "$name: has element $index");
+      var expect = expects[index];
+      Expect.equals(expect, it.current, "$name at $index");
+      Expect.equals(
+          expect, iterable.elementAt(index), "$name: elementAt($index)");
+      Expect.isTrue(iterable.contains(expect), "$name:contains $index");
+    }
+    Expect.isFalse(it.moveNext(),
+        "$name: extra element at ${expects.length}: ${it.current}");
+  } on Error {
+    print("Failed during: $name");
+    rethrow;
+  }
+}
+
+main() {
+  var conversions = <String, Iterable<int> Function(List<int>)>{
+    "const": toConst,
+    "list": toList,
+    "unmod": toUnmodifiable,
+    "set": toSet,
+    "queue": toQueue,
+    "eff-len-iter": toELIter,
+    "non-eff-iter": toNEIter,
+    "typed": toTyped,
+    "keys": toKeys,
+    "values": toValues,
+  };
+  for (var data in [
+    const <int>[],
+    const <int>[1],
+    const <int>[1, 2, 3]
+  ]) {
+    conversions.forEach((name, c) {
+      test(data, c(data).whereType<int>(), "$name#${data.length}.wt<int>");
+      test(data, c(data).whereType<num>(), "$name#${data.length}.wt<num>");
+      test([], c(data).whereType<Null>(), "$name#${data.length}.wt<Null>");
+    });
+  }
+
+  test([1, 0.1], ["a", 1, new Object(), 0.1, null].whereType<num>(), "mixed");
+
+  var o = new Object();
+  var a = new A();
+  var b = new B();
+  var c = new C();
+  var d = new D();
+  var n = null;
+  test([o, a, b, c, d, n], [o, a, b, c, d, n].whereType<Object>(), "Object");
+  test([a, b, c, d], [o, a, b, c, d, n].whereType<A>(), "A");
+  test([b, d], [o, a, b, c, d, n].whereType<B>(), "B");
+  test([c, d], [o, a, b, c, d, n].whereType<C>(), "C");
+  test([d], [o, a, b, c, d, n].whereType<D>(), "D");
+  test([n], [o, a, b, c, d, n].whereType<Null>(), "Null");
+
+  test([d], <B>[d].whereType<C>(), "Unrelated");
+}
+
+class A {}
+
+class B implements A {}
+
+class C implements A {}
+
+class D implements B, C {}
+
+List<int> toConst(List<int> elements) => elements; // Argument is const.
+List<int> toList(List<int> elements) => elements.toList();
+List<int> toUnmodifiable(List<int> elements) =>
+    new List<int>.unmodifiable(elements);
+Set<int> toSet(List<int> elements) => elements.toSet();
+Queue<int> toQueue(List<int> elements) => new Queue<int>.from(elements);
+// Creates an efficient-length iterable.
+Iterable<int> toELIter(List<int> elements) => elements.map<int>((x) => x);
+// Creates a non-efficient-length iterable.
+Iterable<int> toNEIter(List<int> elements) => elements.where((x) => true);
+List<int> toTyped(List<int> elements) => new Int32List.fromList(elements);
+Iterable<int> toKeys(List<int> elements) =>
+    new Map<int, int>.fromIterables(elements, elements).keys;
+Iterable<int> toValues(List<int> elements) =>
+    new Map<int, int>.fromIterables(elements, elements).values;
diff --git a/tests/corelib_2/map_unmodifiable_cast_test.dart b/tests/corelib_2/map_unmodifiable_cast_test.dart
index 9c1e19bcb53..3091337d528 100644
--- a/tests/corelib_2/map_unmodifiable_cast_test.dart
+++ b/tests/corelib_2/map_unmodifiable_cast_test.dart
@@ -8,45 +8,76 @@ import "package:expect/expect.dart";
 import 'dart:collection';
 
 void main() {
-  test(const {1: 37});
-  test(new UnmodifiableMapView({1: 37}));
+  testNum(const {1: 37}, "const");
+  testNum(const <num, num>{1: 37}.cast<int, int>(), "const.cast");
+  testNum(const <num, num>{1: 37}.retype<int, int>(), "const.retype");
 
-  test(new UnmodifiableMapView<num, num>(<num, num>{1: 37}));
-  test(new UnmodifiableMapView<num, num>(<int, int>{1: 37}));
+  testNum(new UnmodifiableMapView({1: 37}), "unmod");
+  testNum(new UnmodifiableMapView<num, num>(<num, num>{1: 37}), "unmod.cast");
+  testNum(new UnmodifiableMapView<num, num>(<int, int>{1: 37}), "unmod.retype");
 
-  test(new UnmodifiableMapView<num, num>(<num, num>{1: 37}).cast<int, int>());
-  test(new UnmodifiableMapView<num, num>(<int, int>{1: 37}).cast<int, int>());
-  test(new UnmodifiableMapView<Object, Object>(<num, num>{1: 37})
-      .cast<int, int>());
-  test(new UnmodifiableMapView<Object, Object>(<int, int>{1: 37})
-      .cast<num, num>());
+  testNum(new UnmodifiableMapView<num, num>(<num, num>{1: 37}).cast<int, int>(),
+      "unmodView<num>.cast<int>");
+  testNum(new UnmodifiableMapView<num, num>(<int, int>{1: 37}).cast<int, int>(),
+      "unmodView<int>.cast<int>");
+  testNum(
+      new UnmodifiableMapView<Object, Object>(<num, num>{1: 37})
+          .cast<int, int>(),
+      "unmodView<Object>(num).cast<int>");
+  testNum(
+      new UnmodifiableMapView<Object, Object>(<int, int>{1: 37})
+          .cast<num, num>(),
+      "unmodView<Object>(int).cast<num>");
 
-  test(new UnmodifiableMapView<num, num>(<num, num>{1: 37}).retype<int, int>());
-  test(new UnmodifiableMapView<num, num>(<int, int>{1: 37}).retype<int, int>());
-  test(new UnmodifiableMapView<Object, Object>(<num, num>{1: 37})
-      .retype<int, int>());
-  test(new UnmodifiableMapView<Object, Object>(<int, int>{1: 37})
-      .retype<num, num>());
+  testNum(
+      new UnmodifiableMapView<num, num>(<num, num>{1: 37}).retype<int, int>(),
+      "unmodView<num>(num).retype<int>");
+  testNum(
+      new UnmodifiableMapView<num, num>(<int, int>{1: 37}).retype<int, int>(),
+      "unmodView<num>(int).retype<int>");
+  testNum(
+      new UnmodifiableMapView<Object, Object>(<num, num>{1: 37})
+          .retype<int, int>(),
+      "unmodView<Object>(num).retype<int>");
+  testNum(
+      new UnmodifiableMapView<Object, Object>(<int, int>{1: 37})
+          .retype<num, num>(),
+      "unmodView<Object>(int).retype<num>");
 
   var m2 = new Map<num, num>.unmodifiable({1: 37});
-  test(m2);
-  test(m2.cast<int, int>());
+  testNum(m2, "Map<num>.unmod");
+  testNum(m2.cast<int, int>(), "Map<num>.unmod.cast<int>");
+
+  Map<Symbol, dynamic> nsm = new NsmMap().foo(a: 0);
+  test(nsm, #a, 0, "nsm");
+  test(nsm.cast<Object, int>(), #a, 0, "nsm.cast");
+  test(nsm.retype<Object, int>(), #a, 0, "nsm.retype");
 }
 
-void test(Map map) {
-  Expect.isTrue(map.containsKey(1));
-  Expect.equals(1, map.length);
-  Expect.equals(1, map.keys.first);
-  Expect.equals(37, map.values.first);
-
-  Expect.throws(map.clear);
-  Expect.throws(() {
-    map.remove(1);
-  });
-  Expect.throws(() {
-    map[2] = 42;
-  });
-  Expect.throws(() {
-    map.addAll(<int, int>{2: 42});
-  });
+void testNum(Map<Object, Object> map, String name) {
+  test(map, 1, 37, name);
+}
+
+void test(
+    Map<Object, Object> map, Object firstKey, Object firstValue, String name) {
+  Expect.isTrue(map.containsKey(firstKey), "$name.containsKey");
+  Expect.equals(1, map.length, "$name.length");
+  Expect.equals(firstKey, map.keys.first, "$name.keys.first");
+  Expect.equals(firstValue, map.values.first, "$name.values.first");
+
+  Expect.throwsUnsupportedError(map.clear, "$name.clear");
+  Expect.throwsUnsupportedError(() {
+    map.remove(firstKey);
+  }, "$name.remove");
+  Expect.throwsUnsupportedError(() {
+    map[null] = null;
+  }, "$name[]=");
+  Expect.throwsUnsupportedError(() {
+    map.addAll(<Null, Null>{null: null});
+  }, "$name.addAll");
+}
+
+class NsmMap {
+  noSuchMethod(i) => i.namedArguments;
+  foo({a, b, c, d});
 }