Fix pretty printer for WebCore::KURL.

From what I can tell, this hasn't worked since abarth cleaned up KURL in
https://src.chromium.org/viewvc/blink?view=rev&revision=150064.

R=tony@chromium.org

Review URL: https://codereview.chromium.org/22999015

git-svn-id: svn://svn.chromium.org/blink/trunk@156165 bbb929c8-8fbe-4397-9dbb-9b2b20218538