IDL compiler: omit header for WindowMediaSource.idl in Python

Source/bindings/scripts/unstable/interface_dependency_resolver.py

 # Copyright (C) 2013 Google Inc. All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 # notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 # copyright notice, this list of conditions and the following disclaimer
@@ skipping 147 matching lines @@
         if key in DEPENDENCY_EXTENDED_ATTRIBUTES)
 
     # C++ class name of the implementation, stored in [ImplementedBy], which
     # defaults to the basename of dependency IDL file.
     # This can be overridden by [ImplementedAs] on the dependency interface.
     # Note that [ImplementedAs] is used with different meanings on interfaces
     # and members:
     # for Blink class name and function name (or constant name), respectively.
     # Thus we do not want to copy this from the interface to the member, but
     # instead extract it and handle it separately.
-    implemented_by = dependency_interface.extended_attributes.get('ImplementedAs', dependency_interface_basename)
+    merged_extended_attributes['ImplementedBy'] = (
+        dependency_interface.extended_attributes.get(
+            'ImplementedAs', dependency_interface_basename))
 
     def merge_lists(source_list, target_list):
         for member in source_list:
             member.extended_attributes.update(merged_extended_attributes)
-            member.extended_attributes['ImplementedBy'] = implemented_by
-            target_list.append(member)
+        target_list.extend(source_list)
 
     merge_lists(dependency_interface.attributes, target_interface.attributes)
     merge_lists(dependency_interface.constants, target_interface.constants)
     merge_lists(dependency_interface.operations, target_interface.operations)