Bug 251657 – avoid creating ElementRareData when lang="" matches the effective document language

• Status: RESOLVED
• Resolution: FIXED
• Component: DOM

[Cameron McCormack (:heycam)]

On Wikipedia, there's a lang="" attribute on the <div> that contains the article content.  On the page I'm looking at, this lang="" matches the value on the document element.  Currently we'll create ElementRareData to store the effective language for the entire subtree, which for large articles can be several MB worth.  We can optimize this by detecting when the explicitly set lang="" matches the effective document language, and avoid the subtree traversal / restyle / ElementRareData creation.

[Radar WebKit Bug Importer]

<rdar://problem/104987630>

[Cameron McCormack (:heycam)]

Pull request: https://github.com/WebKit/WebKit/pull/9566

[Cameron McCormack (:heycam)]

Pull request: https://github.com/WebKit/WebKit/pull/9580

[EWS]

Committed 259931@main (8858f1de792a): <https://commits.webkit.org/259931@main>

Reviewed commits have been landed. Closing PR #9580 and removing active labels.

[Darin Adler]

Since this landed the !hasLanguageAttribute() assertion has been firing when running regression tests on bots:

https://ews-build.s3-us-west-2.amazonaws.com/macOS-AppleSilicon-Ventura-Debug-WK2-Tests-EWS/72c673b1-6062/css3/masking/mask-svg-no-fragmentId-tiled-crash-log.txt

https://ews-build.s3-us-west-2.amazonaws.com/macOS-AppleSilicon-Ventura-Debug-WK2-Tests-EWS/72c673b1-6062/fast/css/large-font-size-crash-crash-log.txt

https://ews-build.s3-us-west-2.amazonaws.com/macOS-AppleSilicon-Ventura-Debug-WK2-Tests-EWS/72c673b1-6062/imported/w3c/web-platform-tests/css/css-pseudo/first-letter-with-span-crash-log.txt

https://ews-build.s3-us-west-2.amazonaws.com/macOS-AppleSilicon-Ventura-Debug-WK2-Tests-EWS/72c673b1-6062/imported/w3c/web-platform-tests/css/selectors/invalidation/lang-pseudo-class-in-has-xhtml-crash-log.txt

[WebKit Commit Bot]

Re-opened since this is blocked by bug 251932

[Ryan Haddad]

Reverted in https://commits.webkit.org/260019@main due to the assertion failures.

[Cameron McCormack (:heycam)]

*** Bug 251904 has been marked as a duplicate of this bug. ***

[Cameron McCormack (:heycam)]

Pull request: https://github.com/WebKit/WebKit/pull/9833

[EWS]

Committed 260047@main (f31c6cd34376): <https://commits.webkit.org/260047@main>

Reviewed commits have been landed. Closing PR #9833 and removing active labels.