service worker: Remove unregister.html test that is already in WPT.

This test is nearly identical to unregister.https.html. The only differences
are the test uses waitUntil() in the message event and it uses a non-existent
page for a scope instead of a blank page. Remove unregister.html and add
waitUntil() calls to unregister.https.html.

Bug: 452910, 688116
Change-Id: I41c42ae090837eceaf90d3b3c7c4f6383c4ef821
Reviewed-on: https://chromium-review.googlesource.com/753202
Reviewed-by: Marijn Kruisselbrink <mek@chromium.org>
Commit-Queue: Matt Falkenhagen <falken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#513927}
3 files changed