[webkit-changes] [WebKit/WebKit] 225ae0: AX: Move AXPosition off the main thread for Scroll...

[AndresGonzalezApple]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: 225ae0791abfaedbe265b8ee4efce54a519f4e0c
      https://github.com/WebKit/WebKit/commit/225ae0791abfaedbe265b8ee4efce54a519f4e0c
  Author: Andres Gonzalez <andresg_22 at apple.com>
  Date:   2023-05-12 (Fri, 12 May 2023)

  Changed paths:
    M Source/WebCore/accessibility/isolatedtree/AXIsolatedObject.cpp
    M Source/WebCore/accessibility/isolatedtree/AXIsolatedTree.cpp
    M Source/WebCore/accessibility/isolatedtree/AXIsolatedTree.h
    M Source/WebCore/accessibility/mac/WebAccessibilityObjectWrapperMac.mm

  Log Message:
  -----------
  AX: Move AXPosition off the main thread for ScrollView and WebArea objects during the isolated tree construction.
https://bugs.webkit.org/show_bug.cgi?id=256644
<rdar://problem/109205791>

Reviewed by Chris Fleizach and Tyler Wilcock.

- Added the AXIsolatedTree::createEmptyContent method to allow for the customization of the Scrollview and WebArea properties for the empty, temporary isolated tree.
- Cache the ScreenRelativePosition for these objects in the empty isolated tree so that it is not needed to hit the main thread upon client's request of this property.
- Some code re-factoring was needed, namely, the addition of AXIsolatedTree::resolveAppends() and queueAppendsAndRemovals.

Canonical link: https://commits.webkit.org/264008@main