Remove errors.dart in dart2js compiler.

lib/compiler/implementation/lib/errors.dart

Index: lib/compiler/implementation/lib/errors.dart
diff --git a/lib/compiler/implementation/lib/errors.dart b/lib/compiler/implementation/lib/errors.dart
deleted file mode 100644
index f125cb2c813541f8233403f2022122de763b1d6d..0000000000000000000000000000000000000000
--- a/lib/compiler/implementation/lib/errors.dart
+++ /dev/null
@@ -1,32 +0,0 @@
-// 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.
-
-// TODO(4910): Shouldn't this file be in the coreimpl and not the core
-// library?
-
-class TypeErrorImplementation implements TypeError {
-  final String msg;
-  const TypeErrorImplementation(String this.msg);
-  String toString() => msg;
-}
-
-/** Thrown by the 'as' operator if the cast isn't valid. */
-class CastExceptionImplementation implements CastException {
-  // TODO(lrn): Change actualType and expectedType to "Type" when reified
-  // types are available.
-  final Object actualType;
-  final Object expectedType;
-
-  CastExceptionImplementation(this.actualType, this.expectedType);
-
-  String toString() {
-    return "CastException: Casting value of type $actualType to"
-           " incompatible type $expectedType";
-  }
-}
-
-class FallThroughErrorImplementation implements FallThroughError {
-  const FallThroughErrorImplementation();
-  String toString() => "Switch case fall-through.";
-}