1791036 - [wpt-sync] Sync PR 35912 - CSS highlight painting: use old spelling/grammar in some edge cases

Status: RESOLVED FIXED

(Core :: Layout: Generated Content, Lists, and Counters, task, P4)

Description

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Sync web-platform-tests PR 35912 into mozilla-central (this bug is closed when the sync is complete).

PR: https://github.com/web-platform-tests/wpt/pull/35912
Details from upstream follow.

Delan Azabani <[e-mail]> wrote:

CSS highlight painting: use old spelling/grammar in some edge cases

SVG decoration painting is broken for highlight pseudos, because it
walks up the ancestors to find ‘fill’ and ‘stroke’ in a way that only
makes sense for originating elements and tree-abiding pseudos, which
can crash if a highlight pseudo has decorations but the originating
content does not. This was fixed in CL:3646539, but the new spelling
and grammar highlight painting in CL:3779861 reintroduced the bug.

PaintOneSpellingGrammarDecoration also asserts that styles will exist
for ::{spelling,grammar}-error, which is generally true due to the new
rules in html.css, but the assertion can fail in non-HTML content or
in HTML content with the wrong root (such as body with no html [2]).

In both of these cases, it probably makes sense to paint the default
spelling/grammar decorations anyway, but this is not yet possible
because there’s no easy way to synthesise a TextDecorationInfo without
a real ComputedStyle. Thankfully the old pre-CSS spelling/grammar
decoration painting code has not yet been removed.

This patch makes PaintOneSpellingGrammarDecoration use the old pre-CSS
spelling/grammar decoration for SVG content and in the rare case where
non-SVG content has no ::{spelling,grammar}-error styles.

[1] https://github.com/w3c/svgwg/issues/894
[2] https://bucket.daz.cat/work/igalia/0/56.html

Fixed: 1358810, 1359175
Change-Id: I33b3499b1c3c21c9b1619ba18ca78305fa9b27f4
Reviewed-on: https://chromium-review.googlesource.com/3899651
WPT-Export-Revision: ab69bf500a54eee8f5484967ee24225a331140b3

Comment 1

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Pushed to try (stability) https://treeherder.mozilla.org/#/jobs?repo=try&revision=252443f31894d296d7656f41035ecf189b5df9d4

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/d07db0b50d00
[wpt PR 35912] - CSS highlight painting: use old spelling/grammar in some edge cases, a=testonly

Comment 3

[Marian-Vasile Laza]

https://hg.mozilla.org/mozilla-central/rev/d07db0b50d00