Oilpan: move ImageData to the oilpan heap.

Source/core/html/HTMLCanvasElement.cpp

 /*
  * Copyright (C) 2004, 2006, 2007 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alp Toker <alp@atoker.com>
  * Copyright (C) 2010 Torch Mobile (Beijing) Co. Ltd. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 366 matching lines @@
         exceptionState.throwSecurityError("Tainted canvases may not be exported.");
         return String();
     }
 
     if (m_size.isEmpty() || !buffer())
         return String("data:,");
 
     String encodingMimeType = toEncodingMimeType(mimeType);
 
     // Try to get ImageData first, as that may avoid lossy conversions.
-    RefPtr<ImageData> imageData = getImageData();
+    RefPtrWillBeRawPtr<ImageData> imageData = getImageData();
 
     if (imageData)
         return ImageDataToDataURL(ImageDataBuffer(imageData->size(), imageData->data()), encodingMimeType, quality);
 
     if (m_context)
         m_context->paintRenderingResultsToCanvas();
 
     return buffer()->toDataURL(encodingMimeType, quality);
 }
 
-PassRefPtr<ImageData> HTMLCanvasElement::getImageData()
+PassRefPtrWillBeRawPtr<ImageData> HTMLCanvasElement::getImageData()
 {
     if (!m_context || !m_context->is3d())
         return nullptr;
     return toWebGLRenderingContext(m_context.get())->paintRenderingResultsToImageData();
 }
 
 SecurityOrigin* HTMLCanvasElement::securityOrigin() const
 {
     return document().securityOrigin();
 }
@@ skipping 244 matching lines @@
 {
     return !originClean();
 }
 
 FloatSize HTMLCanvasElement::sourceSize() const
 {
     return FloatSize(width(), height());
 }
 
 }