Remove usage of dart:json.

tools/dom/templates/html/impl/impl_Window.darttemplate

 // 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 $LIBRARYNAME;
 
 $if DART2JS
 $(ANNOTATIONS)$(CLASS_MODIFIERS)class $CLASSNAME$EXTENDS$IMPLEMENTS native "Window,DOMWindow" {
 $else
 $(ANNOTATIONS)$(CLASS_MODIFIERS)class $CLASSNAME$EXTENDS$IMPLEMENTS$NATIVESPEC {
@@ skipping 14 matching lines @@
   }
   /**
    * Lookup a port by its [name].  Return null if no port is
    * registered under [name].
    */
   SendPortSync lookupPort(String name) {
     var portStr = document.documentElement.attributes['dart-port:$name'];
     if (portStr == null) {
       return null;
     }
-    var port = json.parse(portStr);
+    var port = JSON.decode(portStr);
     return _deserialize(port);
   }
 
   /**
    * Register a [port] on this window under the given [name].  This
    * port may be retrieved by any isolate (or JavaScript script)
    * running in this window.
    */
   void registerPort(String name, var port) {
     var serialized = _serialize(port);
     document.documentElement.attributes['dart-port:$name'] =
-        json.stringify(serialized);
+        JSON.encode(serialized);
   }
 
   /**
    * Deregister a [port] on this window under the given [name].  This
    * port may be retrieved by any isolate (or JavaScript script)
    * running in this window.
    */
   void deregisterPort(String name) {
     document.documentElement.attributes.remove('dart-port:$name');
   }
@@ skipping 290 matching lines @@
       return wrapped.returnValue;
     });
 
     return controller.stream;
   }
 
   String getEventType(EventTarget target) {
     return _eventType;
   }
 }