Size checking logic is duplicated.

Source/core/html/canvas/CanvasRenderingContext2D.cpp

 /*
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2007 Alp Toker <alp@atoker.com>
  * Copyright (C) 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008 Dirk Schulze <krit@webkit.org>
  * Copyright (C) 2010 Torch Mobile (Beijing) Co. Ltd. All rights reserved.
  * Copyright (C) 2012, 2013 Intel Corporation. All rights reserved.
  * Copyright (C) 2013 Adobe Systems Incorporated. All rights reserved.
  *
@@ skipping 1900 matching lines @@
     canvas()->didDraw(dirtyRect);
 }
 
 GraphicsContext* CanvasRenderingContext2D::drawingContext() const
 {
     return canvas()->drawingContext();
 }
 
 static PassRefPtr<ImageData> createEmptyImageData(const IntSize& size)
 {
-    Checked<int, RecordOverflow> dataSize = 4;
-    dataSize *= size.width();
-    dataSize *= size.height();
-    if (dataSize.hasOverflowed())
-        return nullptr;
+    if (RefPtr<ImageData> data = ImageData::create(size)) {
+        data->data()->zeroFill();
+        return data.release();
+    }
 
-    RefPtr<ImageData> data = ImageData::create(size);
-    data->data()->zeroFill();
-    return data.release();
+    return nullptr;
 }
 
 PassRefPtr<ImageData> CanvasRenderingContext2D::createImageData(PassRefPtr<ImageData> imageData, ExceptionState& exceptionState) const
 {
     if (!imageData) {
         exceptionState.throwDOMException(NotSupportedError, ExceptionMessages::argumentNullOrIncorrectType(1, "ImageData"));
         return nullptr;
     }
 
     return createEmptyImageData(imageData->size());
@@ skipping 608 matching lines @@
     const int focusRingWidth = 5;
     const int focusRingOutline = 0;
     c->drawFocusRing(path, focusRingWidth, focusRingOutline, focusRingColor);
 
     c->restore();
 
     didDraw(dirtyRect);
 }
 
 } // namespace WebCore