Fix wheel event dispatch logic to fallback to document when hit-test fails

Source/core/paint/DeprecatedPaintLayer.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
  *   Randall Jesup <rjesup@wgate.com>
@@ skipping 1585 matching lines @@
     if (request.ignoreClipping())
         hitTestArea.unite(LayoutRect(layoutObject()->view()->documentRect()));
 
     DeprecatedPaintLayer* insideLayer = hitTestLayer(this, 0, result, hitTestArea, hitTestLocation, false);
     if (!insideLayer) {
         // We didn't hit any layer. If we are the root layer and the mouse is -- or just was -- down,
         // return ourselves. We do this so mouse events continue getting delivered after a drag has
         // exited the WebView, and so hit testing over a scrollbar hits the content document.
         // In addtion, it is possible for the mouse to stay in the document but there is no element.
         // At that time, the events of the mouse should be fired.
+        // TODO(majidvp): This should apply more consistently across different event types and we
+        // should not use RequestType for it. Perhaps best for it to be done at a higher level. See
+        // http://crbug.com/505825
         LayoutPoint hitPoint = hitTestLocation.point();
         if (!request.isChildFrameHitTest() && ((request.active() || request.release()) || (request.move() && hitTestArea.contains(hitPoint.x(), hitPoint.y()))) && isRootLayer()) {
             layoutObject()->updateHitTestResult(result, toLayoutView(layoutObject())->flipForWritingMode(hitTestLocation.point()));
             insideLayer = this;
         }
     }
 
     // Now determine if the result is inside an anchor - if the urlElement isn't already set.
     Node* node = result.innerNode();
     if (node && !result.URLElement())
@@ skipping 1147 matching lines @@
 
 void showLayerTree(const blink::LayoutObject* layoutObject)
 {
     if (!layoutObject) {
         fprintf(stderr, "Cannot showLayerTree. Root is (nil)\n");
         return;
     }
     showLayerTree(layoutObject->enclosingLayer());
 }
 #endif