Generate FrameTree::uniqueName with a URL attribute value.

Source/web/WebFrameImpl.cpp

Index: Source/web/WebFrameImpl.cpp
diff --git a/Source/web/WebFrameImpl.cpp b/Source/web/WebFrameImpl.cpp
index 96837b342d43cf35bb245fdae7df6b50821393ad..5ba2714b8e31fb4822c4aaf337584f1c063c0d93 100644
--- a/Source/web/WebFrameImpl.cpp
+++ b/Source/web/WebFrameImpl.cpp
@@ -1688,7 +1688,11 @@ PassRefPtr<LocalFrame> WebFrameImpl::createChildFrame(const FrameLoadRequest& re
     RefPtr<LocalFrame> childFrame = LocalFrame::create(&webframe->m_frameLoaderClientImpl, frame()->host(), ownerElement);
     webframe->setWebCoreFrame(childFrame);
 
-    childFrame->tree().setName(request.frameName());
+    // FIXME: Using subResourceAttributeName as fallback is not a perfect
+    // solution. subResourceAttributeName returns just one attribute name. The
+    // element might not have the attribute, and there might be other attributes
+    // which can identify the element.
+    childFrame->tree().setName(request.frameName(), ownerElement->getAttribute(ownerElement->subResourceAttributeName()));
 
     // FIXME: This comment is not quite accurate anymore.
     // LocalFrame::init() can trigger onload event in the parent frame,