https://searchfox.org/mozilla-central/source/testing/web-platform/meta/webvtt/rendering/cues-with-video/processing-model/navigate_cue_position.html.ini

if fission: ERROR

The DOM Fission team is relying on feature teams to debug and fix Fission failures in their tests. If the failure looks like a bug in Fission's DOM or IPC changes, you can send the bug back to me.

We're hoping to enable Fission for a subset of Nightly users in early Q3, so we would like WPT tests to be green for Fission by end of Q2. Whether a particular test failure actually blocks shipping Fission is up to the discretion of the feature team. You all would know better than the DOM Fission which test failures are most important.

You can enable Fission when running WPT tests locally using mach wpt --enable-fission.

Hi, Chris,
I got this error The wpt command does not accept the arguments: --enable-fission when I tried to use --enable-fission.

(In reply to Alastor Wu [:alwu] from comment #2)

I got this error The wpt command does not accept the arguments: --enable-fission when I tried to use --enable-fission.

Sorry about that! I commented before the --enable-fission flag was merged to mozilla-central. The flag has now been merged and I see it in mach help wpt:

--enable-fission      Enable fission in Gecko (defaults to disabled).
--no-enable-fission   Disable fission in Gecko.

When running this test under Fission, I saw this error UnknownError: SecurityError: Permission denied to access property "windowUtils" on cross-origin object and I guess this might be the root cause.

The result of reftest is like following, so I guess the test fails due to the above reason and we haven't started the comparasion yet.

REFTEST   IMAGE 1 (TEST): data:image/png;base64,
REFTEST   IMAGE 2 (REFERENCE): data:image/png;base64,

Per comment4, it looks like a DOM issue.

Chris, when looking at the test it seems it is doing a history.back() within a data: URI iframe [1]. A more generic questions, what's the state of data: URIs with fission at the moment? Is it possible that we are ending up in the wrong process when doing a history back on a data URI?

[1] https://searchfox.org/mozilla-central/rev/c80fa7258c935223fe319c5345b58eae85d4c6ae/testing/web-platform/tests/webvtt/rendering/cues-with-video/processing-model/navigate_cue_position.html#18

(In reply to Christoph Kerschbaumer [:ckerschb] from comment #6)

Chris, when looking at the test it seems it is doing a history.back() within a data: URI iframe [1]. A more generic questions, what's the state of data: URIs with fission at the moment? Is it possible that we are ending up in the wrong process when doing a history back on a data URI?

Peter, do you know the current state of data: URIs and history with Fission?

(In reply to Alastor Wu [:alwu] from comment #4)

When running this test under Fission, I saw this error UnknownError: SecurityError: Permission denied to access property "windowUtils" on cross-origin object and I guess this might be the root cause.

I think this SecurityError is Marionette bug 1574508.

Tracking WPT Fission bugs for Fission M6b (Q2)

Because this bug's Severity has not been changed from the default since it was filed, and it's Priority is P3 (Backlog,) indicating it has been triaged, the bug's Severity is being updated to S3 (normal.)

Fixed by bug 1635904.