e2335b7

[GFC] Support fixed-length padding on grid items
https://bugs.webkit.org/show_bug.cgi?id=319430
<rdar://182249991>

Reviewed by NOBODY (OOPS!).

Narrow and rename the padding avoidance reason (now GridItemHasPercentOrCalcPadding)
so grid items whose padding is a fixed length (px, em, etc) use GFC instead of the
legacy RenderGrid.

Fixed-length padding is threaded into item and track sizing as part of the
item's border-box size, so it lays out identically to legacy RenderGrid.

Percentage and calc() padding remain on the legacy path for now.

* LayoutTests/fast/css-grid-layout/grid-item-with-em-padding-track-sizing-expected.txt: Added.
* LayoutTests/fast/css-grid-layout/grid-item-with-em-padding-track-sizing.html: Added.
* LayoutTests/fast/css-grid-layout/grid-item-with-fixed-padding-and-percent-margin-expected.txt: Added.
* LayoutTests/fast/css-grid-layout/grid-item-with-fixed-padding-and-percent-margin.html: Added.
* LayoutTests/fast/css-grid-layout/grid-item-with-fixed-padding-intrinsic-track-sizing-expected.txt: Added.
* LayoutTests/fast/css-grid-layout/grid-item-with-fixed-padding-intrinsic-track-sizing.html: Added.
* LayoutTests/fast/css-grid-layout/grid-item-with-fixed-padding-track-sizing-expected.txt: Added.
* LayoutTests/fast/css-grid-layout/grid-item-with-fixed-padding-track-sizing.html: Added.
* Source/WebCore/layout/integration/grid/LayoutIntegrationGridCoverage.cpp:
(WebCore::LayoutIntegration::gridLayoutAvoidanceReason):
(WebCore::LayoutIntegration::printReason):

e2335b7

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