service worker: WPT: Add test for XHR Document's URL.

Bug: 915126
Change-Id: I967a72b1e2317af4ddd0be1144f505ebb80948d8
Reviewed-on: https://chromium-review.googlesource.com/c/1415231
Commit-Queue: Matt Falkenhagen <falken@chromium.org>
Reviewed-by: Ben Kelly <wanderview@chromium.org>
Cr-Commit-Position: refs/heads/master@{#623528}
3 files changed