IDL: Union type support for attributes

Source/bindings/scripts/v8_types.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 613 matching lines @@
 
     assignment = '%s = %s' % (variable_name, cpp_value)
     if declare_variable:
         return '%s %s' % (this_cpp_type, assignment)
     return assignment
 
 
 IdlTypeBase.v8_value_to_local_cpp_value = v8_value_to_local_cpp_value
 
 
+def use_output_parameter_for_result(idl_type):
+    """True when methods/getters which return the given idl_type should
+    take the output argument.
+    """
+    return idl_type.is_dictionary or idl_type.is_union_type
+
+IdlTypeBase.use_output_parameter_for_result = property(use_output_parameter_for_result)
+
+
 ################################################################################
 # C++ -> V8
 ################################################################################
 
 def preprocess_idl_type(idl_type):
     if idl_type.is_enum:
         # Enumerations are internally DOMStrings
         return IdlType('DOMString')
     if (idl_type.name in ['Any', 'Object'] or idl_type.is_callback_function):
         return IdlType('ScriptValue')
@@ skipping 220 matching lines @@
 
 
 def is_explicit_nullable(idl_type):
     # Nullable type that isn't implicit nullable (see above.) For such types,
     # we use Nullable<T> or similar explicit ways to represent a null value.
     return idl_type.is_nullable and not idl_type.is_implicit_nullable
 
 IdlTypeBase.is_implicit_nullable = property(is_implicit_nullable)
 IdlUnionType.is_implicit_nullable = False
 IdlTypeBase.is_explicit_nullable = property(is_explicit_nullable)