context.addHitRegion should return if the DOMException occurs.

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 2375 matching lines @@
     }
 
     Path specifiedPath = m_path;
     specifiedPath.transform(state().m_transform);
 
     if (context->isClipMode()) {
         // FIXME: The hit regions should take clipping region into account.
         // However, we have no way to get the region from canvas state stack by now.
         // See http://crbug.com/387057
         exceptionState.throwDOMException(NotSupportedError, "The specified path has no pixels.");
+        return;
     }
 
     passOptions.path = specifiedPath;
     addHitRegionInternal(passOptions, exceptionState);
 }
 
 void CanvasRenderingContext2D::addHitRegionInternal(const HitRegionOptions& options, ExceptionState& exceptionState)
 {
     if (!m_hitRegionManager)
         m_hitRegionManager = HitRegionManager::create();
@@ skipping 29 matching lines @@
 
 unsigned CanvasRenderingContext2D::hitRegionsCount() const
 {
     if (m_hitRegionManager)
         return m_hitRegionManager->getHitRegionsCount();
 
     return 0;
 }
 
 } // namespace WebCore