Enable the WebIDL [Exposed] annotation on an interface's members.

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 78 matching lines @@
         'argument_cpp_type': idl_type.cpp_type_args(used_as_rvalue_type=True),
         'cached_attribute_validation_method': extended_attributes.get('CachedAttribute'),
         'conditional_string': v8_utilities.conditional_string(attribute),
         'constructor_type': idl_type.constructor_type_name
                             if is_constructor_attribute(attribute) else None,
         'cpp_name': cpp_name(attribute),
         'cpp_type': idl_type.cpp_type,
         'cpp_type_initializer': idl_type.cpp_type_initializer,
         'deprecate_as': v8_utilities.deprecate_as(attribute),  # [DeprecateAs]
         'enum_validation_expression': idl_type.enum_validation_expression,
+        'exposed_test': v8_utilities.exposed(attribute, interface),  # [Exposed]
         'has_custom_getter': has_custom_getter(attribute),
         'has_custom_setter': has_custom_setter(attribute),
         'has_type_checking_unrestricted': has_type_checking_unrestricted,
         'idl_type': str(idl_type),  # need trailing [] on array for Dictionary::ConversionContext::setConversionType
         'is_call_with_execution_context': v8_utilities.has_extended_attribute_value(attribute, 'CallWith', 'ExecutionContext'),
         'is_call_with_script_state': v8_utilities.has_extended_attribute_value(attribute, 'CallWith', 'ScriptState'),
         'is_check_security_for_node': is_check_security_for_node,
         'is_custom_element_callbacks': is_custom_element_callbacks,
         'is_expose_js_accessors': 'ExposeJSAccessors' in extended_attributes,
         'is_getter_raises_exception':  # [RaisesException]
@@ skipping 384 matching lines @@
     lambda self: strip_suffix(self.base_type, 'Constructor'))
 
 
 def is_constructor_attribute(attribute):
     # FIXME: replace this with [ConstructorAttribute] extended attribute
     return attribute.idl_type.base_type.endswith('Constructor')
 
 
 def constructor_getter_context(interface, attribute, context):
     context['needs_constructor_getter_callback'] = context['measure_as'] or context['deprecate_as']