Oilpan: move ImageData to the oilpan heap.

Source/core/html/canvas/CanvasRenderingContext2D.h

Index: Source/core/html/canvas/CanvasRenderingContext2D.h
diff --git a/Source/core/html/canvas/CanvasRenderingContext2D.h b/Source/core/html/canvas/CanvasRenderingContext2D.h
index 4c24639d023d23ff25c102d45353b1e1da69c88a..c5b9efadd002a6999f58f16aa4f27baf7a0b752a 100644
--- a/Source/core/html/canvas/CanvasRenderingContext2D.h
+++ b/Source/core/html/canvas/CanvasRenderingContext2D.h
@@ -193,9 +193,9 @@ public:
     PassRefPtr<CanvasGradient> createRadialGradient(float x0, float y0, float r0, float x1, float y1, float r1, ExceptionState&);
     PassRefPtr<CanvasPattern> createPattern(CanvasImageSource*, const String& repetitionType, ExceptionState&);
 
-    PassRefPtr<ImageData> createImageData(PassRefPtr<ImageData>, ExceptionState&) const;
-    PassRefPtr<ImageData> createImageData(float width, float height, ExceptionState&) const;
-    PassRefPtr<ImageData> getImageData(float sx, float sy, float sw, float sh, ExceptionState&) const;
+    PassRefPtrWillBeRawPtr<ImageData> createImageData(PassRefPtrWillBeRawPtr<ImageData>, ExceptionState&) const;
+    PassRefPtrWillBeRawPtr<ImageData> createImageData(float width, float height, ExceptionState&) const;
+    PassRefPtrWillBeRawPtr<ImageData> getImageData(float sx, float sy, float sw, float sh, ExceptionState&) const;
     void putImageData(ImageData*, float dx, float dy, ExceptionState&);
     void putImageData(ImageData*, float dx, float dy, float dirtyX, float dirtyY, float dirtyWidth, float dirtyHeight, ExceptionState&);