When resolving URL, empty relative URL should remove ref component. R=brettw BUG=16 TEST=none Patch by [email protected] Original review http://codereview.chromium.org/600087 git-svn-id: http://google-url.googlecode.com/svn/trunk@122 8873c55e-713a-0410-88f8-23d9c3d90b1b