The element under mouse should be in hover state even if its not inActiveChain.

Source/core/dom/Document.cpp

Index: Source/core/dom/Document.cpp
diff --git a/Source/core/dom/Document.cpp b/Source/core/dom/Document.cpp
index b69cf2e04871d5bcbfef8fe95af8bd0c5ba78658..dd773c4461a2bde75cfd3ea1f12b3700dd91410f 100644
--- a/Source/core/dom/Document.cpp
+++ b/Source/core/dom/Document.cpp
@@ -5478,14 +5478,14 @@ void Document::updateHoverActiveState(const HitTestRequest& request, Element* in
 
         // 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()))
+            if (curr->node() && !curr->isText() && (!mustBeInActiveChain || curr->node()->inActiveChain() || curr == oldHoverObj))

[Rick Byers, 2014/06/12 18:24:06]

This doesn't look like the right fix to me.  How does your patch change the
behavior of this (more general) test case: http://jsbin.com/rider/2/?  If we're
going to fix this bug then I'd expect Chrome's behavior to match Firefox -
namely that hover is cleared on all nodes that are no longer under the mouse and
applied to all nodes that are now under the mouse.  You seem to be special
casing the innermost node here.

Also the behavior we have today seems to be intentional given this comment
above: 
  // If the mouse is down and if this is a mouse move event, we want to restrict
changes in
  // :hover/:active to only apply to elements that are in the :active chain that
we froze
  // at the time the mouse went down.

Changing this seems reasonable to me (I see no reason to freeze the hover chain,
but freezing the active chain makes sense).  But you should update the comment
and overall structure of this code to do that, and make sure you're handling all
the different sub-cases consistently.  Perhaps you just need to remove the
'mustBeInActiveChain' logic?

                 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()))
+        if (curr->node() && !curr->isText() && (!mustBeInActiveChain || curr->node()->inActiveChain() || curr == newHoverObj))
             nodesToAddToChain.append(curr->node());
     }