Make pseudo-classes selector queries work on DocumentFragment

Source/core/dom/ContainerNode.h

Index: Source/core/dom/ContainerNode.h
diff --git a/Source/core/dom/ContainerNode.h b/Source/core/dom/ContainerNode.h
index 99543d230c3308ecd517eb6de1b2df2dfaff6469..6cec25d805b6856e3646fe434786156d295374c2 100644
--- a/Source/core/dom/ContainerNode.h
+++ b/Source/core/dom/ContainerNode.h
@@ -323,6 +323,12 @@ inline ContainerNode* Node::parentElementOrShadowRoot() const
     return parent && (parent->isElementNode() || parent->isShadowRoot()) ? parent : 0;
 }
 
+inline ContainerNode* Node::parentElementOrDocumentFragment() const
+{
+    ContainerNode* parent = parentNode();
+    return parent && (parent->isElementNode() || parent->isDocumentFragment()) ? parent : 0;
+}
+
 // This constant controls how much buffer is initially allocated
 // for a Node Vector that is used to store child Nodes of a given Node.
 // FIXME: Optimize the value.