Adding missing 'part of html' statements.

sdk/lib/html/src/native_DOMPublic.dart

 // Copyright (c) 2011, 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 html;
+
 // This API is exploratory.
 spawnDomFunction(Function topLevelFunction) => _Utils.spawnDomFunctionImpl(topLevelFunction);
 
 // testRunner implementation.
 // FIXME: provide a separate lib for testRunner.
 
 var _testRunner;
 
 TestRunner get testRunner {
   if (_testRunner == null)
     _testRunner = new TestRunner._(_NPObject.retrieve("testRunner"));
   return _testRunner;
 }
 
 class TestRunner {
   final _NPObject _npObject;
 
   TestRunner._(this._npObject);
 
   display() => _npObject.invoke('display');
   dumpAsText() => _npObject.invoke('dumpAsText');
   notifyDone() => _npObject.invoke('notifyDone');
   setCanOpenWindows() => _npObject.invoke('setCanOpenWindows');
   waitUntilDone() => _npObject.invoke('waitUntilDone');
 }