[ServiceWorker] Enable running wpt test clients-get-cross-origin-frame.html

This CL removes the mark [Skip] for clients-get-cross-origin-frame.html
because it can PASS now.

BUG=658997
TEST=blink_tests
external/wpt/service-workers/service-worker/clients-get-cross-origin.https.html

Change-Id: I96738e226ef5dc4cfb5b7b68f18e5e4df1c68d79
Reviewed-on: https://chromium-review.googlesource.com/532854
Reviewed-by: Matt Falkenhagen <falken@chromium.org>
Commit-Queue: Han Leon <leon.han@intel.com>
Cr-Commit-Position: refs/heads/master@{#479312}
1 file changed