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Following from <https://bugs.webkit.org/show_bug.cgi?id=29564#c20>:
Both the Apple and Chromium Windows ports render the height of a button incorrectly if it is specified as a percentage and the button is within an ambient container whose height is unspecified (i.e. auto).
In particular, both the Apple and Chromium Windows ports fail the test
(when run by hand) with respect to percentage button heights.
Note, the reason that the test does not fail under Apple Windows DRT is because Apple Windows DRT uses the Mac theme for controls instead of the native Windows theme, see bug #25592.
I don't think this is incorrect. The test-case assumes mac-specific behaviour, and should probably be split into a generic and mac-only part.
Note: qt, chromium (non-mac), win and gtk all fails these 3 specific sub-tests of fast/replaced/table-percent-height.html