Revert r12819 to look at IE fix offline.

lib/html/scripts/systemnative.py

Index: lib/html/scripts/systemnative.py
===================================================================
--- lib/html/scripts/systemnative.py	(revision 12822)
+++ lib/html/scripts/systemnative.py	(working copy)
@@ -11,10 +11,6 @@
 import systembase
 from generator import *
 
-_dart_custom_members = set([
-    'Window.webkitCancelAnimationFrame',
-    'Window.webkitRequestAnimationFrame',
-    ])
 
 class NativeImplementationSystem(systembase.System):
 
@@ -546,19 +542,12 @@
     self._GenerateNativeBinding('numericIndexSetter', 3, dart_declaration,
         'Callback', True)
 
-  def _HasCustomImplementation(self, member_name):
-    member_name = '%s.%s' % (self._html_interface_name, member_name)
-    return member_name in _dart_custom_members
-
   def AddOperation(self, info, html_name):
     """
     Arguments:
       info: An OperationInfo object.
     """
 
-    if self._HasCustomImplementation(info.name):
-      return
-
     operation = info.operations[0]
 
     if 'CheckSecurityForNode' in operation.ext_attrs: