ServiceWorker: Add new WPT tests to make sure to update a registration with different script type and identical script content.

[chromium-wpt-export-bot]

These tests check that a registration is updated correctly with
different script type. At first Service Worker is registered as
classic script type, then it is re-registered as module script type,
and vice versa. A main script is identical.

Bug: 824647
Change-Id: I2a3f87da1013f84c6e9495f362899dfe6ab97b45
Reviewed-on: https://chromium-review.googlesource.com/c/1298822
Commit-Queue: Asami Doi <[email protected]>
Reviewed-by: Hiroki Nakagawa <[email protected]>
Reviewed-by: Matt Falkenhagen <[email protected]>
Cr-Commit-Position: refs/heads/master@{#604551}

---

Edited by @foolip to include a follow-up fix:

ServiceWorker: Deflake update-with-script-type.https.html

To sheriff: Please re-disable the test if it's still flaky.

In this test file, some tests start re-registering the second service worker
before the first service worker gets activated. In my theory, this sometimes
squashes the second registration job into the first registration job, and
results in test flakiness. This CL makes sure the second register runs after
the first service worker gets activated.

Note that it would be the correct behavior that the second registration job
isn't squashed when the script type is changed. There is a spec issue about
this: https://github.com/w3c/ServiceWorker/issues/1358

Bug: 901317
Change-Id: I7ce379071a35ef9aeb98e4492d651ee6fc4714ec
Reviewed-on: https://chromium-review.googlesource.com/c/1328546
Reviewed-by: Makoto Shimazu <[email protected]>
Commit-Queue: Hiroki Nakagawa <[email protected]>
Cr-Commit-Position: refs/heads/master@{#607494}

[wpt-pr-bot]

Already reviewed downstream.

[Hexcles]

@d0iasm the test seems to be flaky on Firefox. Can you take a look?

Test	Subtest	Results	Messages
/service-workers/service-worker/update-registration-with-type.https.html	Does not update the registration with the same script type and the same main script.	FAIL: 2/10, PASS: 8/10	promise_test: Unhandled rejection with value: object "Error: wait_for_state must be passed a ServiceWorker"

[rakuco]

FTR, I also sent a ping in the Gerrit review a week ago, and the test's been marked as flaky in Blink: https://bugs.chromium.org/p/chromium/issues/detail?id=901317

[foolip]

A CL to deflake the test was landed in https://chromium-review.googlesource.com/c/1328546 and failure to export that CL is now blocking export. I'll cherry-pick it onto this branch and see if that fixes the problem here too.

[foolip]

ci_stability on Travis is still things this is flaky in Firefox. I've tried to repro locally by reloading the test manually over and over without success, and also by running ./wpt run --install-browser --verify firefox service-workers/service-worker/update-registration-with-type.https.html without issue.

@jugglinmike, this is a PR that should come up in your scripts as having different stability results from Travis and Taskcluster.

I'll admin merge this now.