diff --git a/sdk/lib/_internal/compiler/implementation/ssa/optimize.dart b/sdk/lib/_internal/compiler/implementation/ssa/optimize.dart
index a9c1983d3a7..ad89572fceb 100644
--- a/sdk/lib/_internal/compiler/implementation/ssa/optimize.dart
+++ b/sdk/lib/_internal/compiler/implementation/ssa/optimize.dart
@@ -439,7 +439,8 @@ class SsaConstantFolder extends HBaseVisitor implements OptimizationPhase {
     HType leftType = left.instructionType;
     HType rightType = right.instructionType;
 
-    // We don't optimize on numbers to preserve the runtime semantics.
+    // Intersection of int and double return conflicting, so
+    // we don't optimize on numbers to preserve the runtime semantics.
     if (!(left.isNumberOrNull() && right.isNumberOrNull()) &&
         leftType.intersection(rightType, compiler).isConflicting()) {
       return graph.addConstantBool(false, constantSystem);
diff --git a/sdk/lib/_internal/compiler/implementation/ssa/types.dart b/sdk/lib/_internal/compiler/implementation/ssa/types.dart
index ec73cb0e10a..f24f863b476 100644
--- a/sdk/lib/_internal/compiler/implementation/ssa/types.dart
+++ b/sdk/lib/_internal/compiler/implementation/ssa/types.dart
@@ -416,6 +416,7 @@ class HBooleanType extends HPrimitiveType {
     if (other.isUnknown()) return HType.BOOLEAN;
     if (other.isBooleanOrNull()) return HType.BOOLEAN;
     if (other.isBoolean()) return HType.BOOLEAN;
+    if (other.isTop(compiler)) return HType.BOOLEAN;
     return HType.CONFLICTING;
   }
 }
@@ -453,7 +454,7 @@ class HNumberOrNullType extends HPrimitiveOrNullType {
     if (other.isIntegerOrNull()) return HType.INTEGER_OR_NULL;
     if (other.isDoubleOrNull()) return HType.DOUBLE_OR_NULL;
     if (other.isNumberOrNull()) return HType.NUMBER_OR_NULL;
-    if (other.isTop(compiler)) {
+    if (other.canBePrimitiveNumber(compiler)) {
       return other.canBeNull() ? this : HType.NUMBER;
     }
     if (other.canBeNull()) return HType.NULL;
@@ -493,6 +494,7 @@ class HNumberType extends HPrimitiveType {
     if (other.isIntegerOrNull()) return HType.INTEGER;
     if (other.isDoubleOrNull()) return HType.DOUBLE;
     if (other.isNumberOrNull()) return HType.NUMBER;
+    if (other.canBePrimitiveNumber(compiler)) return HType.NUMBER;
     return HType.CONFLICTING;
   }
 }
@@ -531,7 +533,7 @@ class HIntegerOrNullType extends HNumberOrNullType {
     if (other.isDoubleOrNull()) return HType.NULL;
     if (other.isNumber()) return HType.INTEGER;
     if (other.isNumberOrNull()) return HType.INTEGER_OR_NULL;
-    if (other.isTop(compiler)) {
+    if (other.canBePrimitiveNumber(compiler)) {
       return other.canBeNull() ? this : HType.INTEGER;
     }
     if (other.canBeNull()) return HType.NULL;
@@ -574,6 +576,7 @@ class HIntegerType extends HNumberType {
     if (other.isDoubleOrNull()) return HType.CONFLICTING;
     if (other.isNumber()) return HType.INTEGER;
     if (other.isNumberOrNull()) return HType.INTEGER;
+    if (other.canBePrimitiveNumber(compiler)) return HType.INTEGER;
     return HType.CONFLICTING;
   }
 }
@@ -612,7 +615,7 @@ class HDoubleOrNullType extends HNumberOrNullType {
     if (other.isDoubleOrNull()) return HType.DOUBLE_OR_NULL;
     if (other.isNumber()) return HType.DOUBLE;
     if (other.isNumberOrNull()) return HType.DOUBLE_OR_NULL;
-    if (other.isTop(compiler)) {
+    if (other.canBePrimitiveNumber(compiler)) {
       return other.canBeNull() ? this : HType.DOUBLE;
     }
     if (other.canBeNull()) return HType.NULL;
@@ -655,6 +658,7 @@ class HDoubleType extends HNumberType {
     if (other.isDoubleOrNull()) return HType.DOUBLE;
     if (other.isNumber()) return HType.DOUBLE;
     if (other.isNumberOrNull()) return HType.DOUBLE;
+    if (other.canBePrimitiveNumber(compiler)) return HType.DOUBLE;
     return HType.CONFLICTING;
   }
 }
diff --git a/tests/corelib/corelib.status b/tests/corelib/corelib.status
index 089101bdfb9..28cc8f8fb4c 100644
--- a/tests/corelib/corelib.status
+++ b/tests/corelib/corelib.status
@@ -41,9 +41,6 @@ string_base_vm_test: Fail, OK # VM specific test.
 
 string_replace_func_test: Skip # Bug 6554 - doesn't terminate.
 
-[ $compiler == dart2js && $checked ]
-string_codeunits_test: Fail # Issue 8904
-
 [ $compiler == dart2js && $runtime == none ]
 *: Fail, Pass # TODO(ahe): Triage these tests.
 
diff --git a/tests/language/type_intersection_test.dart b/tests/language/type_intersection_test.dart
new file mode 100644
index 00000000000..a6e260372cf
--- /dev/null
+++ b/tests/language/type_intersection_test.dart
@@ -0,0 +1,18 @@
+// Copyright (c) 2013, 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.
+
+// Regression test for dart2js that used to consider that the
+// intersection of [Comparable] and [num] is conflicting.
+
+class A {
+  foo(a, Comparable b) => a == b;
+  bar(a, Comparable b) => b == a;
+}
+
+main() {
+  Expect.isFalse(new A().foo(1, 'foo'));
+  Expect.isTrue(new A().foo(1, 1));
+  Expect.isFalse(new A().bar(1, 'foo'));
+  Expect.isTrue(new A().bar(1, 1));
+}