bindings: Supports inheritance of [Unforgeable] attributes as accessor-type properties.

Source/bindings/scripts/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 106 matching lines @@
         'has_custom_setter': has_custom_setter(attribute),
         'has_setter': has_setter(attribute),
         'idl_type': str(idl_type),  # need trailing [] on array for Dictionary::ConversionContext::setConversionType
         'is_call_with_execution_context': has_extended_attribute_value(attribute, 'CallWith', 'ExecutionContext'),
         'is_call_with_script_state': has_extended_attribute_value(attribute, 'CallWith', 'ScriptState'),
         'is_check_security_for_frame': is_check_security_for_frame,
         'is_check_security_for_node': is_check_security_for_node,
         'is_check_security_for_window': is_check_security_for_window,
         'is_custom_element_callbacks': is_custom_element_callbacks,
         # TODO(yukishiino): Make all DOM attributes accessor-type properties.
-        'is_data_type_property': constructor_type or interface.name == 'Window' or interface.name == 'Location' or (interface.name == 'Event' and attribute.name == 'isTrusted'),
+        'is_data_type_property': constructor_type or interface.name == 'Window' or interface.name == 'Location',
         'is_getter_raises_exception':  # [RaisesException]
             'RaisesException' in extended_attributes and
             extended_attributes['RaisesException'] in (None, 'Getter'),
         'is_implemented_in_private_script': is_implemented_in_private_script,
         'is_keep_alive_for_gc': keep_alive_for_gc,
         'is_lenient_this': 'LenientThis' in extended_attributes,
         'is_nullable': idl_type.is_nullable,
         'is_explicit_nullable': idl_type.is_explicit_nullable,
         'is_partial_interface_member':
             'PartialInterfaceImplementedAs' in extended_attributes,
@@ skipping 370 matching lines @@
     return attribute.idl_type.name.endswith('Constructor')
 
 
 def update_constructor_attribute_context(interface, attribute, context):
     context['needs_constructor_getter_callback'] = context['measure_as'] or context['deprecate_as']
     # When the attribute name is the same as the interface name, do not generate
     # callback functions for each attribute and use
     # {{cpp_class}}ConstructorAttributeSetterCallback.  Otherwise, generate
     # a callback function in order to hard-code the attribute name.
     context['needs_constructor_setter_callback'] = context['name'] != context['constructor_type']