Make the VM's dart:core and dart:async library patches clean.

sdk/lib/core/errors.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.
 
 part of dart.core;
 
 /**
  * Error objects thrown in the case of a program failure.
  *
  * An `Error` object represents a program failure that the programmer
@@ skipping 396 matching lines @@
 /**
  * Error thrown when control reaches the end of a switch case.
  *
  * The Dart specification requires this error to be thrown when
  * control reaches the end of a switch case (except the last case
  * of a switch) without meeting a break or similar end of the control
  * flow.
  */
 class FallThroughError extends Error {
   FallThroughError();
+
+  external String toString();
 }
 
 /**
  * Error thrown when trying to instantiate an abstract class.
  */
 class AbstractClassInstantiationError extends Error {
   final String _className;
-  AbstractClassInstantiationError(String this._className);
-  String toString() => "Cannot instantiate abstract class: '$_className'";
+  AbstractClassInstantiationError(String className) : _className = className;
+
+  external String toString();
 }
 
 
 /**
  * Error thrown by the default implementation of [:noSuchMethod:] on [Object].
  */
 class NoSuchMethodError extends Error {
   final Object _receiver;
   final Symbol _memberName;
   final List _arguments;
@@ skipping 16 matching lines @@
    * empty list.
    *
    * The [namedArguments] is a map from [Symbol]s to the values of named
    * arguments that the method was called with.
    *
    * The optional [existingArgumentNames] is the expected parameters of a
    * method with the same name on the receiver, if available. This is
    * the signature of the method that would have been called if the parameters
    * had matched.
    */
-  NoSuchMethodError(Object receiver,
-                    Symbol memberName,
-                    List positionalArguments,
-                    Map<Symbol ,dynamic> namedArguments,
-                    [List existingArgumentNames = null])
-      : _receiver = receiver,
-        _memberName = memberName,
-        _arguments = positionalArguments,
-        _namedArguments = namedArguments,
-        _existingArgumentNames = existingArgumentNames;
+  external NoSuchMethodError(Object receiver,
+                             Symbol memberName,
+                             List positionalArguments,
+                             Map<Symbol, dynamic> namedArguments,
+                             [List existingArgumentNames = null]);
 
   external String toString();
 }
 
 
 /**
  * The operation was not allowed by the object.
  *
  * This [Error] is thrown when an instance cannot implement one of the methods
  * in its signature.
@@ skipping 82 matching lines @@
  * the first time it is read. If evaluating the initializer expression causes
  * another read of the variable, this error is thrown.
  */
 class CyclicInitializationError extends Error {
   final String variableName;
   CyclicInitializationError([this.variableName]);
   String toString() => variableName == null
       ? "Reading static variable during its initialization"
       : "Reading static variable '$variableName' during its initialization";
 }