1767176 - CSS Parsing Done Incorrectly since 04.27 Update

Status: RESOLVED DUPLICATE of bug 1766909

(Core :: CSS Parsing and Computation, defect)

Description

[qjfkcovb3]

Attachment: about_support.txt

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:101.0) Gecko/20100101 Firefox/101.0

Steps to reproduce:

All extensions transitioning light <-> dark CSS do not work correctly since 04.27 update. (e.g. Dark Reader)

Already contacted Dark Reader dev team, and figured that it was due to changed implemented by Nightly.

Link:

https://github.com/darkreader/darkreader/issues/8789

Actual results:

For picture illustration:

https://ibb.co/p0WkfrV

Expected results:

.

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

The Bugbug bot thinks this bug should belong to the 'Core::CSS Parsing and Computation' component, and is moving the bug to that component. Please correct in case you think the bot is wrong.

Comment 2

[bbhtt]

I think I have the regression range for it, but I'm not 100% certain since the issue is appears a bit inconsistently. Note that this affects both Fenix and Firefox Nightly on desktop.

Affected webpages: Random but somewhat prominent on google.com, askubuntu.com etc.

To reproduce:

1. Install Dark Reader in a fresh profile (no settings modification needed).
2. Open some websites for example do a google search.
3. Page is stuck in a transitional state between light <-> dark theme (see screenshot).
4. A few refreshes/toggling the extension on/off makes the page normal but issue appears again on new page load.

$ mozregression --good 2022-04-25 --bad 2022-04-30

Last good revision: 17d94894a53a39e46f1877587f01d7719d7b927d
First bad revision: b5c0bdafaf5ede49311c48d5b143f1b7320e15bb
Pushlog: https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=17d94894a53a39e46f1877587f01d7719d7b927d&tochange=b5c0bdafaf5ede49311c48d5b143f1b7320e15bb

Comment 3

[bbhtt]

Ah, forgot to add that flipping layout.css.constructable-stylesheets.enabled to false seems to fix the issue for me.

Comment 4

[bbhtt]

Looks like duplicate of https://bugzilla.mozilla.org/show_bug.cgi?id=1766909

Comment 5

[BugBot [:suhaib / :marco/ :calixte]]

:emilio, since you are the author of the regressor, bug 1644102, could you take a look?
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