diff --git a/runtime/lib/errors.cc b/runtime/lib/errors.cc
index 7a3415aa0a6..3ef30797059 100644
--- a/runtime/lib/errors.cc
+++ b/runtime/lib/errors.cc
@@ -168,57 +168,6 @@ DEFINE_NATIVE_ENTRY(TypeError_throwNew, 0, 4) {
   return Object::null();
 }
 
-// Allocate and throw a new FallThroughError.
-// Arg0: index of the case clause token into which we fall through.
-// Return value: none, throws an exception.
-DEFINE_NATIVE_ENTRY(FallThroughError_throwNew, 0, 1) {
-  GET_NON_NULL_NATIVE_ARGUMENT(Smi, smi_pos, arguments->NativeArgAt(0));
-  TokenPosition fallthrough_pos = TokenPosition::Deserialize(smi_pos.Value());
-
-  const Array& args = Array::Handle(Array::New(2));
-
-  // Initialize 'url' and 'line' arguments.
-  DartFrameIterator iterator(thread,
-                             StackFrameIterator::kNoCrossThreadIteration);
-  iterator.NextFrame();  // Skip native call.
-  const Script& script = Script::Handle(Exceptions::GetCallerScript(&iterator));
-  args.SetAt(0, String::Handle(script.url()));
-  intptr_t line = -1;
-  script.GetTokenLocation(fallthrough_pos, &line);
-  args.SetAt(1, Smi::Handle(Smi::New(line)));
-
-  Exceptions::ThrowByType(Exceptions::kFallThrough, args);
-  UNREACHABLE();
-  return Object::null();
-}
-
-// Allocate and throw a new AbstractClassInstantiationError.
-// Arg0: Token position of allocation statement.
-// Arg1: class name of the abstract class that cannot be instantiated.
-// Return value: none, throws an exception.
-DEFINE_NATIVE_ENTRY(AbstractClassInstantiationError_throwNew, 0, 2) {
-  GET_NON_NULL_NATIVE_ARGUMENT(Smi, smi_pos, arguments->NativeArgAt(0));
-  GET_NON_NULL_NATIVE_ARGUMENT(String, class_name, arguments->NativeArgAt(1));
-  TokenPosition error_pos = TokenPosition::Deserialize(smi_pos.Value());
-
-  const Array& args = Array::Handle(Array::New(3));
-
-  // Initialize 'className', 'url' and 'line' arguments.
-  DartFrameIterator iterator(thread,
-                             StackFrameIterator::kNoCrossThreadIteration);
-  iterator.NextFrame();  // Skip native call.
-  const Script& script = Script::Handle(Exceptions::GetCallerScript(&iterator));
-  args.SetAt(0, class_name);
-  args.SetAt(1, String::Handle(script.url()));
-  intptr_t line = -1;
-  script.GetTokenLocation(error_pos, &line);
-  args.SetAt(2, Smi::Handle(Smi::New(line)));
-
-  Exceptions::ThrowByType(Exceptions::kAbstractClassInstantiation, args);
-  UNREACHABLE();
-  return Object::null();
-}
-
 // Rethrow an error with a stacktrace.
 DEFINE_NATIVE_ENTRY(Error_throwWithStackTrace, 0, 2) {
   GET_NON_NULL_NATIVE_ARGUMENT(Instance, error, arguments->NativeArgAt(0));
diff --git a/runtime/vm/bootstrap_natives.h b/runtime/vm/bootstrap_natives.h
index 20a2d74e075..271ff4c9139 100644
--- a/runtime/vm/bootstrap_natives.h
+++ b/runtime/vm/bootstrap_natives.h
@@ -152,8 +152,6 @@ namespace dart {
   V(Error_throwWithStackTrace, 2)                                              \
   V(StackTrace_current, 0)                                                     \
   V(TypeError_throwNew, 4)                                                     \
-  V(FallThroughError_throwNew, 1)                                              \
-  V(AbstractClassInstantiationError_throwNew, 2)                               \
   V(Stopwatch_now, 0)                                                          \
   V(Stopwatch_frequency, 0)                                                    \
   V(Timeline_getNextAsyncId, 0)                                                \
diff --git a/sdk/lib/_internal/vm/lib/errors_patch.dart b/sdk/lib/_internal/vm/lib/errors_patch.dart
index aaaf11fbba7..05b0afaa32b 100644
--- a/sdk/lib/_internal/vm/lib/errors_patch.dart
+++ b/sdk/lib/_internal/vm/lib/errors_patch.dart
@@ -134,9 +134,6 @@ class FallThroughError {
   @pragma("vm:entry-point")
   FallThroughError._create(this._url, this._line);
 
-  @pragma("vm:external-name", "FallThroughError_throwNew")
-  external static _throwNew(int caseClausePos);
-
   @patch
   String toString() {
     return "'$_url': Switch case fall-through at line $_line.";
@@ -176,9 +173,6 @@ class AbstractClassInstantiationError {
   AbstractClassInstantiationError._create(
       this._className, this._url, this._line);
 
-  @pragma("vm:external-name", "AbstractClassInstantiationError_throwNew")
-  external static _throwNew(int caseClausePos, String className);
-
   @patch
   String toString() {
     return "Cannot instantiate abstract class $_className: "