Support WebIDL optional default value syntax

Source/bindings/scripts/v8_methods.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 127 matching lines @@
 
 
 def generate_argument(interface, method, argument, index):
     extended_attributes = argument.extended_attributes
     idl_type = argument.idl_type
     this_cpp_value = cpp_value(interface, method, index)
     is_variadic_wrapper_type = argument.is_variadic and idl_type.is_wrapper_type
     return {
         'cpp_type': idl_type.cpp_type_args(used_in_cpp_sequence=is_variadic_wrapper_type),
         'cpp_value': this_cpp_value,
+        'default_value': argument.default_value,
         'enum_validation_expression': idl_type.enum_validation_expression,
         'has_default': 'Default' in extended_attributes,
         'has_event_listener_argument': any(
             argument_so_far for argument_so_far in method.arguments[:index]
             if argument_so_far.idl_type.name == 'EventListener'),
         'has_legacy_overload_string':  # [LegacyOverloadString]
             'LegacyOverloadString' in extended_attributes,
         'has_type_checking_interface':
             (has_extended_attribute_value(interface, 'TypeChecking', 'Interface') or
              has_extended_attribute_value(method, 'TypeChecking', 'Interface')) and
@@ skipping 29 matching lines @@
                 # FIXME: remove this special case by moving get() into
                 # EventTarget::removeEventListener
                 return '%s.get()' % argument.name
             return argument.name
         if (idl_type.is_callback_interface or
             idl_type.name in ['NodeFilter', 'XPathNSResolver']):
             # FIXME: remove this special case
             return '%s.release()' % argument.name
         return argument.name
 
-    # Truncate omitted optional arguments
-    arguments = method.arguments[:number_of_arguments]
     cpp_arguments = v8_utilities.call_with_arguments(method)
     # Members of IDL partial interface definitions are implemented in C++ as
     # static member functions, which for instance members (non-static members)
     # take *impl as their first argument
     if ('PartialInterfaceImplementedAs' in method.extended_attributes and
         not method.is_static):
         cpp_arguments.append('*impl')
-    cpp_arguments.extend(cpp_argument(argument) for argument in arguments)
+    cpp_arguments.extend(cpp_argument(argument)
+                         for argument in method.arguments[:number_of_arguments])
+    cpp_arguments.extend(argument.default_value
+                         for argument in method.arguments[number_of_arguments:]
+                         if argument.is_optional and argument.default_value)
     this_union_arguments = method.idl_type and method.idl_type.union_arguments
     if this_union_arguments:
         cpp_arguments.extend(this_union_arguments)
 
     if 'RaisesException' in method.extended_attributes:
         cpp_arguments.append('exceptionState')
 
     if method.name == 'Constructor':
         base_name = 'create'
     elif method.name == 'NamedConstructor':
@@ skipping 60 matching lines @@
 
 
 def union_arguments(idl_type):
     """Return list of ['result0Enabled', 'result0', 'result1Enabled', ...] for union types, for use in setting return value"""
     return [arg
             for i in range(len(idl_type.member_types))
             for arg in ['result%sEnabled' % i, 'result%s' % i]]
 
 IdlType.union_arguments = property(lambda self: None)
 IdlUnionType.union_arguments = property(union_arguments)