HTML Imports: No more BlockingDocumentCreation.

Source/wtf/TreeNode.h

Index: Source/wtf/TreeNode.h
diff --git a/Source/wtf/TreeNode.h b/Source/wtf/TreeNode.h
index 15c7679bef360329f2e02a4ff30805165a140783..35af98becc8edae96ea0854d46cc38c14a053f00 100644
--- a/Source/wtf/TreeNode.h
+++ b/Source/wtf/TreeNode.h
@@ -135,6 +135,16 @@ public:
         return child;
     }
 
+    void takeChildrenFrom(NodeType* oldParent)
+    {
+        ASSERT(oldParent != this);
+        while (oldParent->hasChildren()) {
+            NodeType* child = oldParent->firstChild();
+            oldParent->removeChild(child);
+            this->appendChild(child);
+        }
+    }
+
 private:
     NodeType* m_next;
     NodeType* m_previous;