[webkit-reviews] review requested: [Bug 91117] Add support for compositing the contents of overflow:scroll areas : [Attachment 158870] Patch

[bugzilla-daemon at webkit.org]

Sami Kyöstilä <skyostil at chromium.org> has asked  for review:
Bug 91117: Add support for compositing the contents of overflow:scroll areas
https://bugs.webkit.org/show_bug.cgi?id=91117

Attachment 158870: Patch
https://bugs.webkit.org/attachment.cgi?id=158870&action=review

------- Additional Comments from Sami Kyöstilä <skyostil at chromium.org>
First pass at fixing some problems with the original patch. Still need to clean
up the tests.

    - Renamed GraphicsLayerPaintAll => GraphicsLayerPaintAllWithOverflowClip
    - Use layer position instead of bounds origin to position scrolling
      content.
    - Fixed scrolling content appearing over overflow controls.
    - Always promote touch scrollable elements to composition layers
      (RLC::requiresCompositingLayer & RLC::requiresOwnBackingStore).
    - Include touch scrolling in RLC::reasonForCompositing()
    - Include touch scrolling in layer memory usage estimate.
    - Fixed some typos and formatting.