Use metadata annotation @patch for patch classes

runtime/lib/object_patch.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.
 
-patch class Object {
+@patch class Object {
 
   // The VM has its own implementation of equals.
   bool operator ==(other) native "Object_equals";
 
   // Helpers used to implement hashCode. If a hashCode is used, we remember it
   // in a weak table in the VM. A new hashCode value is calculated using a
   // number generator.
   static final _hashCodeRnd = new Random();
 
   static _getHash(obj) native "Object_getHash";
   static _setHash(obj, hash) native "Object_setHash";
 
   // Shared static implentation for hashCode and _identityHashCode.
   static int _objectHashCode(obj) {
     var result = _getHash(obj);
     if (result == 0) {
       // We want the hash to be a Smi value greater than 0.
       result = _hashCodeRnd.nextInt(0x40000000);
       while (result == 0) {
         result = _hashCodeRnd.nextInt(0x40000000);
       }
       _setHash(obj, result);
     }
     return result;
   }
 
-  /* patch */ int get hashCode => _objectHashCode(this);
+  /* @patch */ int get hashCode => _objectHashCode(this);
   int get _identityHashCode => _objectHashCode(this);
 
-  /* patch */ String toString() native "Object_toString";
+  /* @patch */ String toString() native "Object_toString";
   // A statically dispatched version of Object.toString.
   static String _toString(obj) native "Object_toString";
 
   _noSuchMethod(bool isMethod,
                 String memberName,
                 int type,
                 List arguments,
                 Map<String, dynamic> namedArguments)
       native "Object_noSuchMethod";
 
-  /* patch */ noSuchMethod(Invocation invocation) {
+  /* @patch */ noSuchMethod(Invocation invocation) {
     return _noSuchMethod(invocation.isMethod,
                          internal.Symbol.getName(invocation.memberName),
                          invocation._type,
                          invocation.positionalArguments,
                          _symbolMapToStringMap(invocation.namedArguments));
   }
 
-  /* patch */ Type get runtimeType native "Object_runtimeType";
+  /* @patch */ Type get runtimeType native "Object_runtimeType";
 
   // Call this function instead of inlining instanceof, thus collecting
   // type feedback and reducing code size of unoptimized code.
   bool _instanceOf(instantiator_type_arguments, type, bool negate)
       native "Object_instanceOf";
 
   // Group of functions for implementing fast simple instance of.
   bool _simpleInstanceOf(type) native "Object_simpleInstanceOf";
   bool _simpleInstanceOfTrue(type) => true;
   bool _simpleInstanceOfFalse(type) => false;
-  
+
   bool _instanceOfDouble(bool negate) native "Object_instanceOfDouble";
   bool _instanceOfNum(bool negate) native "Object_instanceOfNum";
   bool _instanceOfInt(bool negate) native "Object_instanceOfInt";
   bool _instanceOfSmi(bool negate) native "Object_instanceOfSmi";
   bool _instanceOfString(bool negate) native "Object_instanceOfString";
 
   // Call this function instead of inlining 'as', thus collecting type
   // feedback. Returns receiver.
   _as(instantiator_type_arguments, type) native "Object_as";
 
   static _symbolMapToStringMap(Map<Symbol, dynamic> map) {
     var result = new Map<String, dynamic>();
     map.forEach((Symbol key, value) {
       result[internal.Symbol.getName(key)] = value;
     });
     return result;
   }
 }