Oilpan: keep ImageData on the heap by default.

Source/core/html/canvas/CanvasRenderingContext2D.cpp

Index: Source/core/html/canvas/CanvasRenderingContext2D.cpp
diff --git a/Source/core/html/canvas/CanvasRenderingContext2D.cpp b/Source/core/html/canvas/CanvasRenderingContext2D.cpp
index 67a5481e0b97d859abd66c88819b313d36ccf199..b7555853759be36e604a15be6243de8b9bcb1ddc 100644
--- a/Source/core/html/canvas/CanvasRenderingContext2D.cpp
+++ b/Source/core/html/canvas/CanvasRenderingContext2D.cpp
@@ -1553,12 +1553,12 @@ GraphicsContext* CanvasRenderingContext2D::drawingContext() const
     return canvas()->drawingContext();
 }
 
-PassRefPtrWillBeRawPtr<ImageData> CanvasRenderingContext2D::createImageData(PassRefPtrWillBeRawPtr<ImageData> imageData) const
+ImageData* CanvasRenderingContext2D::createImageData(ImageData* imageData) const
 {
     return ImageData::create(imageData->size());
 }
 
-PassRefPtrWillBeRawPtr<ImageData> CanvasRenderingContext2D::createImageData(float sw, float sh, ExceptionState& exceptionState) const
+ImageData* CanvasRenderingContext2D::createImageData(float sw, float sh, ExceptionState& exceptionState) const
 {
     if (!sw || !sh) {
         exceptionState.throwDOMException(IndexSizeError, String::format("The source %s is 0.", sw ? "height" : "width"));
@@ -1578,7 +1578,7 @@ PassRefPtrWillBeRawPtr<ImageData> CanvasRenderingContext2D::createImageData(floa
     return ImageData::create(size);
 }
 
-PassRefPtrWillBeRawPtr<ImageData> CanvasRenderingContext2D::getImageData(float sx, float sy, float sw, float sh, ExceptionState& exceptionState) const
+ImageData* CanvasRenderingContext2D::getImageData(float sx, float sy, float sw, float sh, ExceptionState& exceptionState) const
 {
     if (!canvas()->originClean())
         exceptionState.throwSecurityError("The canvas has been tainted by cross-origin data.");