Clean up callback interface code and template

Source/bindings/templates/callback_interface.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"
 {% filter conditional(conditional_string) %}
 #include "{{v8_class}}.h"
 
@@ skipping 33 matching lines @@
     {% if method.call_with_this_handle %}
     v8::Handle<v8::Value> thisHandle = thisValue.v8Value();
     if (thisHandle.IsEmpty()) {
         if (!isScriptControllerTerminating())
             CRASH();
         {{return_default}};
     }
     ASSERT(thisHandle->IsObject());
     {% endif %}
     {% for argument in method.arguments %}
-    {{argument.cpp_to_v8_conversion | indent}}
-    if ({{argument.name}}Handle.IsEmpty()) {
+    v8::Handle<v8::Value> {{argument.handle}} = {{argument.cpp_value_to_v8_value}};
+    if ({{argument.handle}}.IsEmpty()) {
         if (!isScriptControllerTerminating())
             CRASH();
         {{return_default}};
     }
     {% endfor %}
     {% if method.arguments %}
-    v8::Handle<v8::Value> argv[] = { {{method.handles | join(', ')}} };
+    v8::Handle<v8::Value> argv[] = { {{method.arguments | join(', ', attribute='handle')}} };
     {% else %}
     v8::Handle<v8::Value> *argv = 0;
     {% endif %}
 
     {% set this_handle_parameter = 'v8::Handle<v8::Object>::Cast(thisHandle), ' if method.call_with_this_handle else '' %}
     {% if method.idl_type == 'boolean' %}
     return invokeCallback(m_callback.newLocal(m_isolate), {{this_handle_parameter}}{{method.arguments | length}}, argv, executionContext(), m_isolate);
     {% else %}{# void #}
     invokeCallback(m_callback.newLocal(m_isolate), {{this_handle_parameter}}{{method.arguments | length}}, argv, executionContext(), m_isolate);
     {% endif %}
 }
 
 {% endfor %}
 } // namespace WebCore
 {% endfilter %}