Adding hidden HTMLElement base class back for Dart2JS

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 logging
@@ skipping 486 matching lines @@
       else:
         factory_provider = info.factory_provider_name
 
     implementation_emitter = self._ImplementationEmitter()
 
     base_type_info = None
     if self._interface.parents:
       supertype = self._interface.parents[0].type.id
       if not IsDartCollectionType(supertype) and not IsPureInterface(supertype):
         base_type_info = self._type_registry.TypeInfo(supertype)
-        if base_type_info.merged_into() \
-            and self._backend.ImplementsMergedMembers():
-          base_type_info = self._type_registry.TypeInfo(
-              base_type_info.merged_into())
 
     if base_type_info:
       base_class = base_type_info.implementation_name()
     else:
       base_class = self._backend.RootClassName()
 
     implements = self._backend.AdditionalImplementedInterfaces()
     for parent in self._interface.parents:
       parent_type_info = self._type_registry.TypeInfo(parent.type.id)
       if parent_type_info.interface_name() != base_class and \
@@ skipping 667 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)