[webkit-changes] [WebKit/WebKit] 9dc96c: Simplify repainting logic in RenderLayer::recursiv...

[Simon Fraser]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: 9dc96cf594dd31247f37fa53d3cd000471be0882
      https://github.com/WebKit/WebKit/commit/9dc96cf594dd31247f37fa53d3cd000471be0882
  Author: Simon Fraser <simon.fraser at apple.com>
  Date:   2023-11-09 (Thu, 09 Nov 2023)

  Changed paths:
    M LayoutTests/fast/repaint/hidpi-box-with-subpixel-height-inflates-expected.txt
    M Source/WebCore/rendering/RenderLayer.cpp

  Log Message:
  -----------
  Simplify repainting logic in RenderLayer::recursiveUpdateLayerPositions()
https://bugs.webkit.org/show_bug.cgi?id=264461
rdar://118151709

Reviewed by Alan Baradlay.

The `NeedsFullRepaint` case previously duplicate some logic that exists in `RenderElement::repaintAfterLayoutIfNeeded()`,
which is that if we're doing a full repaint, we just need to paint the clippedOverflowRects.

This logic was optimized in 270370 at main to turn two repaints into one sometimes, and we can re-use it here. We know
that in the RequiresFullRepaint::Yes case, `RenderElement::repaintAfterLayoutIfNeeded()` only consults the clippedOverflowRects,
so we can fold this logic with the second `shouldRepaintAfterLayout()` clause. It's fine to pass empty oldRects if we didn't
have any.

`repaintAfterLayoutIfNeeded()` does the check for printing, so we can remove that. Also the comment duplicates comments
in that function too, so remove it.

* LayoutTests/fast/repaint/hidpi-box-with-subpixel-height-inflates-expected.txt:
* Source/WebCore/rendering/RenderLayer.cpp:
(WebCore::RenderLayer::recursiveUpdateLayerPositions):
(WebCore::RenderLayer::shouldRepaintAfterLayout const):

Canonical link: https://commits.webkit.org/270454@main