Have ScriptPromiseResolver on the Oilpan heap always.

Source/modules/imagebitmap/WindowImageBitmapFactories.cpp

 /*
  * 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
@@ skipping 50 matching lines @@
 
 static IntSize sizeFor(HTMLVideoElement* video)
 {
     if (WebMediaPlayer* webMediaPlayer = video->webMediaPlayer())
         return webMediaPlayer->naturalSize();
     return IntSize();
 }
 
 static ScriptPromise fulfillImageBitmap(ScriptState* scriptState, PassRefPtrWillBeRawPtr<ImageBitmap> imageBitmap)
 {
-    RefPtrWillBeRawPtr<ScriptPromiseResolver> resolver = ScriptPromiseResolver::create(scriptState);
+    ScriptPromiseResolver* resolver = ScriptPromiseResolver::create(scriptState);
     ScriptPromise promise = resolver->promise();
     if (imageBitmap) {
         resolver->resolve(imageBitmap);
     } else {
         resolver->reject(ScriptValue(scriptState, v8::Null(scriptState->isolate())));
     }
     return promise;
 }
 
 ScriptPromise WindowImageBitmapFactories::createImageBitmap(ScriptState* scriptState, EventTarget& eventTarget, HTMLImageElement* image, ExceptionState& exceptionState)
@@ skipping 95 matching lines @@
     if (!sw || !sh) {
         exceptionState.throwDOMException(IndexSizeError, String::format("The source %s provided is 0.", sw ? "height" : "width"));
         return ScriptPromise();
     }
 
     // FIXME: make ImageBitmap creation asynchronous crbug.com/258082
     return fulfillImageBitmap(scriptState, canvas->isPaintable() ? ImageBitmap::create(canvas, IntRect(sx, sy, sw, sh)) : nullptr);
 }
 
 } // namespace blink