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 3407 matching lines @@
     }
 }
 
 void Document::styleResolverMayHaveChanged()
 {
     styleResolverChanged(hasNodesWithPlaceholderStyle() ? FullStyleUpdate : AnalyzedStyleUpdate);
 }
 
 void Document::setHoverNode(PassRefPtrWillBeRawPtr<Node> newHoverNode)
 {
+    if (!newHoverNode) {
+        m_hoverNode.clear();

[Rick Byers, 2014/11/17 22:00:10]

why is this change necessary?  Doesn't it already behave like this?  Eg. try
moving the mouse out of the window - that should call setHoverNode(nullptr)
already today I think.

+        return;
+    }
     m_hoverNode = newHoverNode;
 }
 
 void Document::setActiveHoverElement(PassRefPtrWillBeRawPtr<Element> newActiveElement)
 {
     if (!newActiveElement) {
         m_activeHoverElement.clear();
         return;
     }
 
@@ skipping 1979 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 ((settings() && settings()->viewportEnabled())

[Rick Byers, 2014/11/17 22:00:10]

The logic to decide when to apply this policy belongs in EventHandler, not here
in Document.  The behavior here should be based just on what HitTestRequest
flags are present.  This will be important, for example, when we start caching
HitTestResult objects keyed by their HitTestRequest.

+        && oldHoverObj == newHoverObj && request.touchEvent() && !request.active() && !request.hover()) {
+        // clear the :hover style after Tap, when meta viewport is set
+        for (RenderObject* curr = oldHoverObj; curr; curr = curr->hoverAncestor()) {

[Rick Byers, 2014/11/17 22:00:10]

please don't copy/paste code from above.  We should be able to refactor the code
to unify the "clear old hover" logic in one place.

+            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