[webkit-changes] [WebKit/WebKit] b6dc2f: Accessibility is not informed of changes to severa...

[Tyler Wilcock]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: b6dc2fc14af457482b09b9408bd8aa676d110bb4
      https://github.com/WebKit/WebKit/commit/b6dc2fc14af457482b09b9408bd8aa676d110bb4
  Author: Tyler Wilcock <tyler_w at apple.com>
  Date:   2023-04-14 (Fri, 14 Apr 2023)

  Changed paths:
    M Source/WebCore/dom/Element.cpp
    M Source/WebCore/dom/Element.h

  Log Message:
  -----------
  Accessibility is not informed of changes to several attributes
https://bugs.webkit.org/show_bug.cgi?id=255433
rdar://problem/108030716

Reviewed by Chris Dumez.

Accessibility relies on attribute changes from the DOM to stay up to date, and we are missing quite a few.
This is because accessibility is notified about attribute changes in Element::attributeChanged. However,
this method is virtual, and many subclasses don't call up to Element::attributeChanged. I believe we've
always had this problem for some attributes, but it was worsened with the restructuring in this change:

https://bugs.webkit.org/show_bug.cgi?id=255258 (Drop Element::parseAttribute())

After this change, we stopped receiving updates for the disabled attribute for option elements, the
placeholder attribute for HTMLTextFormControlElement subclasses, and likely more.

This was caught because accessibility/dynamic-attribute-changes-should-update-isenabled.html started failing
in isolated tree mode (--accessibility-isolated-tree test runner flag). This configuration is not in EWS
(post-commit only for now), so this bug couldn't have been caught up-front.

This is performance neutral on Speedometer.

* Source/WebCore/dom/Element.h:
* Source/WebCore/dom/Element.cpp:
(WebCore::Element::notifyAttributeChanged):
Added. Calls the virtual attributeChanged method and unconditionally
notifies accessibility of the change.

(WebCore::Element::attributeChanged):
(WebCore::Element::parserSetAttributes):
(WebCore::Element::didMoveToNewDocument):
(WebCore::Element::didAddAttribute):
(WebCore::Element::didModifyAttribute):
(WebCore::Element::didRemoveAttribute):
(WebCore::Element::cloneAttributesFromElement):
Use notifyAttributeChanged over attributeChanged.

Canonical link: https://commits.webkit.org/262988@main