Distinguish between common and dart2js specific monitored.

tools/dom/scripts/systemhtml.py

 #!/usr/bin/python
 # 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.
 
 """This module provides shared functionality for the system to generate
 Dart:html APIs from the IDL database."""
 
 import emitter
 import monitored
@@ skipping 56 matching lines @@
     'WheelEvent.wheelDeltaX',
     'WheelEvent.wheelDeltaY',
     'Window.cancelAnimationFrame',
     'Window.console',
     'Window.document',
     'Window.indexedDB',
     'Window.location',
     'Window.open',
     'Window.requestAnimationFrame',
     # 'WorkerContext.indexedDB', # Workers
-    ])
+    ], dart2jsOnly=True)
 
 _js_custom_constructors = monitored.Set('systemhtml._js_custom_constructors', [
     'AudioContext',
     'Blob',
     'MutationObserver',
     'RTCIceCandidate',
     'RTCPeerConnection',
     'RTCSessionDescription',
     'SpeechRecognition',
-    ])
+    ], dart2jsOnly=True)
 
 # Classes that offer only static methods, and therefore we should suppress
 # constructor creation.
 _static_classes = set(['Url'])
 
 # Information for generating element constructors.
 #
 # TODO(sra): maybe remove all the argument complexity and use cascades.
 #
 #   var c = new CanvasElement(width: 100, height: 70);
@@ skipping 1056 matching lines @@
     for library_name in libraries:
       self._libraries[library_name] = DartLibrary(
           library_name, template_loader, library_type, output_dir)
 
   def AddFile(self, basename, library_name, path):
     self._libraries[library_name].AddFile(path)
 
   def Emit(self, emitter, auxiliary_dir):
     for lib in self._libraries.values():
       lib.Emit(emitter, auxiliary_dir)