Don't make :hover sticky on tap on sites that set a mobile viewport set

Source/core/dom/Document.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2008, 2009, 2011, 2012 Google Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) Research In Motion Limited 2010-2011. All rights reserved.
@@ skipping 5406 matching lines @@
 
         }
 
         // The old hover path only needs to be cleared up to (and not including) the common ancestor;
         for (RenderObject* curr = oldHoverObj; curr && curr != ancestor; curr = curr->hoverAncestor()) {
             if (curr->node() && !curr->isText() && (!mustBeInActiveChain || curr->node()->inActiveChain()))
                 nodesToRemoveFromChain.append(curr->node());
         }
     }
 
-    // Now set the hover state for our new object up to the root.
-    for (RenderObject* curr = newHoverObj; curr; curr = curr->hoverAncestor()) {
-        if (curr->node() && !curr->isText() && (!mustBeInActiveChain || curr->node()->inActiveChain()))
-            nodesToAddToChain.append(curr->node());
+    if (oldHoverObj == newHoverObj && request.leave()) {
+        // clear hover path upto including the ancestor
+        for (RenderObject* curr = oldHoverObj; curr; curr = curr->hoverAncestor()) {
+            if (curr->node() && !curr->isText() && (!mustBeInActiveChain || curr->node()->inActiveChain())) {
+                nodesToRemoveFromChain.append(curr->node());
+            }
+        }
+        setHoverNode(nullptr);
+    } else {
+        // Now set the hover state for our new object up to the root.
+        for (RenderObject* curr = newHoverObj; curr; curr = curr->hoverAncestor()) {
+            if (curr->node() && !curr->isText() && (!mustBeInActiveChain || curr->node()->inActiveChain()))
+                nodesToAddToChain.append(curr->node());
+        }
     }
 
     // mouseenter and mouseleave events do not bubble, so they are dispatched iff there is a capturing
     // event handler on an ancestor or a normal event handler on the element itself. This special
     // handling is necessary to avoid O(n^2) capturing event handler checks. We'll check the previously
     // hovered node's ancestor tree for 'mouseleave' handlers here, then check the newly hovered node's
     // ancestor tree for 'mouseenter' handlers after dispatching the 'mouseleave' events (as the handler
     // for 'mouseleave' might set a capturing 'mouseenter' handler, odd as that might be).
     bool ancestorHasCapturingMouseleaveListener = false;
     if (event && newHoverNode != oldHoverNode.get()) {
@@ skipping 407 matching lines @@
 #ifndef NDEBUG
 using namespace blink;
 void showLiveDocumentInstances()
 {
     WeakDocumentSet& set = liveDocumentSet();
     fprintf(stderr, "There are %u documents currently alive:\n", set.size());
     for (Document* document : set)
         fprintf(stderr, "- Document %p URL: %s\n", document, document->url().string().utf8().data());
 }
 #endif