[bindings] Support is_explicit_nullable for method arguments.

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 194 matching lines @@
         has_extended_attribute_value(interface, 'TypeChecking', 'Unrestricted') or
         has_extended_attribute_value(method, 'TypeChecking', 'Unrestricted'))
 
     if ('ImplementedInPrivateScript' in extended_attributes and
         not idl_type.is_wrapper_type and
         not idl_type.is_basic_type):
         raise Exception('Private scripts supports only primitive types and DOM wrappers.')
 
     set_default_value = argument.set_default_value
     return {
-        'cpp_type': idl_type.cpp_type_args(extended_attributes=extended_attributes,
-                                           raw_type=True,
-                                           used_as_variadic_argument=argument.is_variadic),
+        'cpp_type': (
+            v8_types.cpp_template_type('Nullable', idl_type.cpp_type)
+            if idl_type.is_explicit_nullable
+            else idl_type.cpp_type_args(

[Jens Widell, 2015/03/02 07:53:13]

I think it would be better to move this call to idl_type.cpp_type_args() up,
storing the result in a variable ('this_cpp_type' is commonly used for that
purpose) and then use that variable in both branches here.

Also, the condition for using Nullable<> should also technically be
"idl_type.is_explicit_nullable and not argument.is_variadic".

+                extended_attributes=extended_attributes,
+                raw_type=True,
+                used_as_variadic_argument=argument.is_variadic)),
         'cpp_value': this_cpp_value,
         # FIXME: check that the default value's type is compatible with the argument's
         'set_default_value': set_default_value,
         'enum_validation_expression': idl_type.enum_validation_expression,
         'handle': '%sHandle' % argument.name,
         # FIXME: remove once [Default] removed and just use argument.default_value
         'has_default': 'Default' in extended_attributes or set_default_value,
         'has_type_checking_interface': type_checking_interface,
         # Dictionary is special-cased, but arrays and sequences shouldn't be
         'idl_type': idl_type.base_type,
         'idl_type_object': idl_type,
         'index': index,
         'is_callback_function': idl_type.is_callback_function,
         'is_callback_interface': idl_type.is_callback_interface,
         # FIXME: Remove generic 'Dictionary' special-casing
         'is_dictionary': idl_type.is_dictionary or idl_type.base_type == 'Dictionary',
+        'is_explicit_nullable': idl_type.is_explicit_nullable,
         'is_nullable': idl_type.is_nullable,
         'is_optional': argument.is_optional,
         'is_variadic': argument.is_variadic,
         'is_variadic_wrapper_type': is_variadic_wrapper_type,
         'is_wrapper_type': idl_type.is_wrapper_type,
         'name': argument.name,
         'private_script_cpp_value_to_v8_value': idl_type.cpp_value_to_v8_value(
             argument.name, isolate='scriptState->isolate()',
             creation_context='scriptState->context()->Global()'),
         'use_permissive_dictionary_conversion': 'PermissiveDictionaryConversion' in extended_attributes,
@@ skipping 202 matching lines @@
 
 IdlOperation.returns_promise = property(method_returns_promise)
 
 
 def argument_conversion_needs_exception_state(method, argument):
     idl_type = argument.idl_type
     return (idl_type.v8_conversion_needs_exception_state or
             argument.is_variadic or
             (method.returns_promise and (idl_type.is_string_type or
                                          idl_type.is_enum)))