IDL compiler: sync Python to r166698 (and add test case)

Source/bindings/templates/interface.h

 {# http://www.chromium.org/blink/coding-style#TOC-License #}
 /*
  * 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.
@@ skipping 113 matching lines @@
     {% if named_property_getter and
           named_property_getter.is_custom_property_enumerator %}
     static void namedPropertyEnumeratorCustom(const v8::PropertyCallbackInfo<v8::Array>&);
     {% endif %}
     {# END custom special operations #}
     {% if has_custom_legacy_call_as_function %}
     static void legacyCallCustom(const v8::FunctionCallbackInfo<v8::Value>&);
     {% endif %}
     {# Custom internal fields #}
     {% set custom_internal_field_counter = 0 %}
-    {# persistentHandleIndex must be the first field, if it is present #}
-    {% if is_will_be_garbage_collected %}
-    static const int persistentHandleIndex = v8DefaultWrapperInternalFieldCount + {{custom_internal_field_counter}};
-    {% set custom_internal_field_counter = custom_internal_field_counter + 1 %}
-    {% endif %}
     {% if is_event_target and not is_node %}
     {# Event listeners on DOM nodes are explicitly supported in the GC controller. #}
     static const int eventListenerCacheIndex = v8DefaultWrapperInternalFieldCount + {{custom_internal_field_counter}};
     {% set custom_internal_field_counter = custom_internal_field_counter + 1 %}
     {% endif %}
+    {# persistentHandleIndex must be the last field, if it is present.
+       Detailed explanation: https://codereview.chromium.org/139173012
+       FIXME: Remove this internal field, and share one field for either:
+       * a persistent handle (if the object is in oilpan) or
+       * a C++ pointer to the DOM object (if the object is not in oilpan) #}
+    {% if is_will_be_garbage_collected %}
+    static const int persistentHandleIndex = v8DefaultWrapperInternalFieldCount + {{custom_internal_field_counter}};
+    {% set custom_internal_field_counter = custom_internal_field_counter + 1 %}
+    {% endif %}
     static const int internalFieldCount = v8DefaultWrapperInternalFieldCount + {{custom_internal_field_counter}};
     {# End custom internal fields #}
     static inline void* toInternalPointer({{cpp_class}}* impl)
     {
         {% if parent_interface %}
         return V8{{parent_interface}}::toInternalPointer(impl);
         {% else %}
         return impl;
         {% endif %}
     }
@@ skipping 147 matching lines @@
     v8SetReturnValueFast(callbackInfo, impl.get(), wrappable);
 }
 
 {% if has_event_constructor %}
 bool initialize{{cpp_class}}({{cpp_class}}Init&, const Dictionary&, ExceptionState&, const v8::FunctionCallbackInfo<v8::Value>& info, const String& = "");
 
 {% endif %}
 }
 {% endfilter %}
 #endif // {{v8_class}}_h