Teach V8GCController how to traverse TemplateContentDocumentFragment::host

Source/bindings/scripts/unstable/v8_attributes.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 167 matching lines @@
         return CONTENT_ATTRIBUTE_GETTER_NAMES[idl_type]
     if 'URL' in attribute.extended_attributes:
         return 'getURLAttribute'
     return 'fastGetAttribute'
 
 
 def is_keep_alive_for_gc(attribute):
     idl_type = attribute.idl_type
     extended_attributes = attribute.extended_attributes
     return (
-        'KeepAttributeAliveForGC' in extended_attributes or
         # For readonly attributes, for performance reasons we keep the attribute
         # wrapper alive while the owner wrapper is alive, because the attribute
         # never changes.
         (attribute.is_read_only and
          v8_types.is_wrapper_type(idl_type) and
          # There are some exceptions, however:
          not(
              # Node lifetime is managed by object grouping.
              v8_types.is_dom_node_type(idl_type) or
              # A self-reference is unnecessary.
@@ skipping 153 matching lines @@
     if ('NotEnumerable' in extended_attributes or
         is_constructor_attribute(attribute)):
         property_attributes_list.append('v8::DontEnum')
     if 'Unforgeable' in extended_attributes:
         property_attributes_list.append('v8::DontDelete')
     return property_attributes_list or ['v8::None']
 
 
 def is_constructor_attribute(attribute):
     return attribute.idl_type.endswith('Constructor')