Fix broken AttachContext from r152289

Source/core/dom/Element.cpp

Index: Source/core/dom/Element.cpp
diff --git a/Source/core/dom/Element.cpp b/Source/core/dom/Element.cpp
index 4b4c6413ee03f3893f8eb26abed04fb044d1470f..ce49e2ff8e4046a4a705cb7c0d278eb9b6d6d513 100644
--- a/Source/core/dom/Element.cpp
+++ b/Source/core/dom/Element.cpp
@@ -1318,7 +1318,7 @@ void Element::detach(const AttachContext& context)
     }
 
     if (ElementShadow* shadow = this->shadow()) {
-        detachChildrenIfNeeded();
+        detachChildrenIfNeeded(context);
         shadow->detach();

[esprehn, 2013/06/13 18:20:42]

You don't correctly handle ShadowRoots, you need to pass the context down
through shadow->detach and ->attach. Otherwise a :hover around a thing with a
shadow will fail the same as my test case.

     }
     ContainerNode::detach(context);