IDL union: nullable support

Source/bindings/templates/union.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This file has been auto-generated by {{code_generator}}. DO NOT MODIFY!
 
 #include "config.h"
 #include "{{header_filename}}"
 
 {% macro assign_and_return_if_hasinstance(member) %}
@@ skipping 34 matching lines @@
 void {{container.cpp_class}}::trace(Visitor* visitor)
 {
     {% for member in container.members if member.is_traceable %}
     visitor->trace(m_{{member.cpp_name}});
     {% endfor %}
 }
 
 {% endif %}
 void V8{{container.cpp_class}}::toImpl(v8::Isolate* isolate, v8::Handle<v8::Value> v8Value, {{container.cpp_class}}& impl, ExceptionState& exceptionState)
 {
-    {# FIXME: We don't follow the spec on handling null and undefined at this
-       moment. Should be fixed once we implement all necessary conversion steps
-       below. #}
     if (v8Value.IsEmpty())
         return;
 
     {# The numbers in the following comments refer to the steps described in
        http://heycam.github.io/webidl/#es-union
+       NOTE: Step 1 (null or undefined) is handled in *OrNull::toImpl()
        FIXME: Implement all necessary steps #}
     {# 3. Platform objects (interfaces) #}
     {% for interface in container.interface_types %}
     {{assign_and_return_if_hasinstance(interface) | indent}}
 
     {% endfor %}
     {# 8. ArrayBuffer #}
     {% if container.array_buffer_type %}
     {{assign_and_return_if_hasinstance(container.array_buffer_type) | indent}}
 
@@ skipping 74 matching lines @@
         return {{member.cpp_value_to_v8_value}};
     {% endfor %}
     default:
         ASSERT_NOT_REACHED();
     }
     return v8::Handle<v8::Value>();
 }
 
 {% endfor %}
 } // namespace blink