merge class extensions from patch files

test/generated_sdk/lib/core/expando.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;
 
 /**
  * An [Expando] allows adding new properties to objects.
  *
  * Does not work on numbers, strings, booleans or null.
@@ skipping 53 matching lines @@
    */
   void operator[]=(Object object, T value) {
     var values = Primitives.getProperty(object, _EXPANDO_PROPERTY_NAME);
     if (values == null) {
       values = new Object();
       Primitives.setProperty(object, _EXPANDO_PROPERTY_NAME, values);
     }
     Primitives.setProperty(values, _getKey(), value);
   }
 
+  String _getKey() {
+    String key = Primitives.getProperty(this, _KEY_PROPERTY_NAME);
+    if (key == null) {
+      key = "expando\$key\$${_keyCount++}";
+      Primitives.setProperty(this, _KEY_PROPERTY_NAME, key);
+    }
+    return key;
+  }
+
+  static const String _KEY_PROPERTY_NAME = 'expando\$key';
+
+  static const String _EXPANDO_PROPERTY_NAME = 'expando\$values';
+
+  static int _keyCount = 0;
+
 }