[webkit-changes] [WebKit/WebKit] b8d402: Fix negative shadow repaint issue

[Alan Baradlay]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: b8d4023a9816caf4508a2e44694e5a48a79cb910
      https://github.com/WebKit/WebKit/commit/b8d4023a9816caf4508a2e44694e5a48a79cb910
  Author: Alan Baradlay <zalan at apple.com>
  Date:   2023-05-10 (Wed, 10 May 2023)

  Changed paths:
    A LayoutTests/fast/box-shadow/negative-shadow-box-expand-expected.txt
    A LayoutTests/fast/box-shadow/negative-shadow-box-expand.html
    A LayoutTests/fast/box-shadow/negative-shadow-box-shrink-expected.txt
    A LayoutTests/fast/box-shadow/negative-shadow-box-shrink.html
    M Source/WebCore/rendering/RenderElement.cpp

  Log Message:
  -----------
  Fix negative shadow repaint issue
https://bugs.webkit.org/show_bug.cgi?id=251176
<rdar://problem/104749948>

Reviewed by Simon Fraser.

Negative offset value places the box shadow above the bottom edge of the box (and to the left of the right edge).
It turns regular, outset type of shadow into an inset type of damage
since repaint has to happen above the bottom edge (away from the right side).

(test case credits go to https://src.chromium.org/viewvc/blink?view=revision&revision=164709)

* LayoutTests/fast/box-shadow/negative-shadow-box-expand-expected.txt: Added.
* LayoutTests/fast/box-shadow/negative-shadow-box-expand.html: Added.
* LayoutTests/fast/box-shadow/negative-shadow-box-shrink-expected.txt: Added.
* LayoutTests/fast/box-shadow/negative-shadow-box-shrink.html: Added.
* Source/WebCore/rendering/RenderElement.cpp:
(WebCore::RenderElement::repaintAfterLayoutIfNeeded):

Canonical link: https://commits.webkit.org/263899@main