Fix a crash in WebViewImpl::copyImageAt.

Source/web/WebViewImpl.cpp

 /*
  * Copyright (C) 2011, 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 3432 matching lines @@
     scaledPoint.scale(1 / pageScaleFactor(), 1 / pageScaleFactor());
     return hitTestResultForWindowPos(scaledPoint);
 }
 
 void WebViewImpl::copyImageAt(const WebPoint& point)
 {
     if (!m_page)
         return;
 
     HitTestResult result = hitTestResultForWindowPos(point);
-    Node* node = result.innerNonSharedNode();
-    ASSERT(node);
-
-    if (!isHTMLCanvasElement(*node) && result.absoluteImageURL().isEmpty()) {
+    if (!isHTMLCanvasElement(result.innerNonSharedNode()) && result.absoluteImageURL().isEmpty()) {
         // There isn't actually an image at these coordinates.  Might be because
         // the window scrolled while the context menu was open or because the page
         // changed itself between when we thought there was an image here and when
         // we actually tried to retreive the image.
         //
         // FIXME: implement a cache of the most recent HitTestResult to avoid having
         //        to do two hit tests.
         return;
     }
 
@@ skipping 1040 matching lines @@
     return mainFrameImpl()->frameView()->layoutSize().width() == m_size.width
         || (constraints.minimumScale == constraints.maximumScale && constraints.minimumScale != -1);
 }
 
 void WebViewImpl::forceNextWebGLContextCreationToFail()
 {
     WebGLRenderingContext::forceNextWebGLContextCreationToFail();
 }
 
 } // namespace blink