Expose remaining 'errors' in an unified dart:core.

lib/compiler/implementation/lib/mock.dart

 // Copyright (c) 2012, 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.
 
 // Mocks of things that Leg cannot read directly.
 
 // TODO(ahe): Remove this file.
 
-class TypeError extends AssertionError {
+class TypeErrorImplementation implements TypeError {

[Mads Ager (google), 2012/08/28 16:01:46]

How about putting these in errors.dart. That will match the
corelib/src/errors.dart file.

   final String msg;
-  const TypeError(String this.msg);
+  const TypeErrorImplementation(String this.msg);
   String toString() => msg;
 }
 
 /** Thrown by the 'as' operator if the cast isn't valid. */
-class CastException implements TypeError {
+class CastExceptionImplementation implements CastException {
   // TODO(lrn): Change actualType and expectedType to "Type" when reified
   // types are available.
   final Object actualType;
   final Object expectedType;
 
-  CastException(this.actualType, this.expectedType);
+  CastExceptionImplementation(this.actualType, this.expectedType);
 
   String toString() {
     return "CastException: Casting value of type $actualType to"
            " incompatible type $expectedType";
   }
 }
 
 class FallThroughError {
   const FallThroughError();
   String toString() => "Switch case fall-through.";
@@ skipping 17 matching lines @@
 // TODO(ahe): Not sure ByteArray belongs in the core library.
 interface Uint8List extends List default _InternalByteArray {
   Uint8List(int length);
 }
 
 class _InternalByteArray {
   factory Uint8List(int length) {
     throw new UnsupportedOperationException("new Uint8List($length)");
   }
 }