IDL: make optional arguments (without default) explicit sometimes

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 162 matching lines @@
     if base_idl_type in CPP_SPECIAL_CONVERSION_RULES:
         return CPP_SPECIAL_CONVERSION_RULES[base_idl_type]
 
     if base_idl_type in NON_WRAPPER_TYPES:
         return ('PassRefPtr<%s>' if used_as_rvalue_type else 'RefPtr<%s>') % base_idl_type
     if idl_type.is_string_type:
         if not raw_type:
             return 'String'
         return 'V8StringResource<%s>' % string_mode()
 
+    if idl_type.is_callback_interface:
+        ptr_type = 'RefPtr' if base_idl_type == 'EventListener' else 'OwnPtr'
+        return cpp_template_type(ptr_type, base_idl_type)
+
     if idl_type.is_typed_array_element_type and raw_type:
         return base_idl_type + '*'
     if idl_type.is_interface_type:
         implemented_as_class = idl_type.implemented_as
         if raw_type:
             return implemented_as_class + '*'
         new_type = 'Member' if used_in_cpp_sequence else 'RawPtr'
         ptr_type = cpp_ptr_type(('PassRefPtr' if used_as_rvalue_type else 'RefPtr'), new_type, idl_type.gc_type)
         return cpp_template_type(ptr_type, implemented_as_class)
     # Default, assume native type is a pointer with same type name as idl type
@@ skipping 622 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)