Canvas2d: The control in hit region should be a canvas fallback element.

third_party/WebKit/Source/modules/canvas2d/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 2216 matching lines @@
     axObjectCache->setCanvasObjectBounds(element, elementRect);
 }
 
 void CanvasRenderingContext2D::addHitRegion(const HitRegionOptions& options, ExceptionState& exceptionState)
 {
     if (options.id().isEmpty() && !options.control()) {
         exceptionState.throwDOMException(NotSupportedError, "Both id and control are null.");
         return;
     }
 
+    if (options.control() && !canvas()->isSupportedInteractiveCanvasFallback(*options.control())) {
+        exceptionState.throwDOMException(NotSupportedError, "The control is neither null nor a supported interactive canvas fallback element.");
+        return;
+    }
+
     Path hitRegionPath = options.hasPath() ? options.path()->path() : m_path;
 
     SkCanvas* c = drawingCanvas();
 
     if (hitRegionPath.isEmpty() || !c || !state().isTransformInvertible()
         || !c->getClipDeviceBounds(0)) {
         exceptionState.throwDOMException(NotSupportedError, "The specified path has no pixels.");
         return;
     }
 
@@ skipping 108 matching lines @@
         if (imageType == CanvasRenderingContext2DState::NonOpaqueImage)
             return;
         if (alpha < 0xFF)
             return;
     }
 
     canvas()->buffer()->willOverwriteCanvas();
 }
 
 } // namespace blink