Improve spatial navigation on overlapping elements.

Source/core/page/FocusController.cpp

 /*
  * Copyright (C) 2006, 2007 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nuanti Ltd.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 737 matching lines @@
 
     if (candidate.isOffscreenAfterScrolling && candidate.alignment < Full)
         return;
 
     if (closest.isNull()) {
         closest = candidate;
         return;
     }
 
     LayoutRect intersectionRect = intersection(candidate.rect, closest.rect);
-    if (!intersectionRect.isEmpty() && !areElementsOnSameLine(closest, candidate)) {
+    if (!intersectionRect.isEmpty() && !areElementsOnSameLine(closest, candidate)
+        && intersectionRect == candidate.rect) {
         // If 2 nodes are intersecting, do hit test to find which node in on top.
         LayoutUnit x = intersectionRect.x() + intersectionRect.width() / 2;
         LayoutUnit y = intersectionRect.y() + intersectionRect.height() / 2;
         HitTestResult result = candidate.visibleNode->document().page()->mainFrame()->eventHandler().hitTestResultAtPoint(IntPoint(x, y), HitTestRequest::ReadOnly | HitTestRequest::Active | HitTestRequest::IgnoreClipping | HitTestRequest::ConfusingAndOftenMisusedDisallowShadowContent);
         if (candidate.visibleNode->contains(result.innerNode())) {
             closest = candidate;
             return;
         }
         if (closest.visibleNode->contains(result.innerNode()))
             return;
@@ skipping 144 matching lines @@
         startingRect = nodeRectInAbsoluteCoordinates(container, true /* ignore border */);
         container = scrollableEnclosingBoxOrParentFrameForNodeInDirection(type, container);
         if (container && container->isDocumentNode())
             toDocument(container)->updateLayoutIgnorePendingStylesheets();
     } while (!consumed && container);
 
     return consumed;
 }
 
 } // namespace WebCore