Origins with invalid ports should be unique.

We create a unique origin when presented with an out-of-range port, but
don't actually use it. This patch adds a 'return' to ensure that the
unique origin is correctly used.

Ports Jon Lee's patch from https://bugs.webkit.org/show_bug.cgi?id=118652.

Review URL: https://chromiumcodereview.appspot.com/19154004

git-svn-id: svn://svn.chromium.org/blink/trunk@154257 bbb929c8-8fbe-4397-9dbb-9b2b20218538