1940370 - Fix test failures in WPTs stretch-block-size-003.html and stretch-inline-size-003.html

Status: NEW

(Core :: Layout, defect)

Description

[Daniel Holbert [:dholbert]]

Bug 1940367 changes WPTs stretch-block-size-003.html and stretch-inline-size-003.html and introduces some new expected-failures in those tests, in Firefox. At first glance, I think we might be mishandling the border and padding on the stretched abspos elements.

I'm filing this bug to take a look and address these test-failures.

Comment 1

[Daniel Holbert [:dholbert]]

Attachment: testcase 1

Here's a reduced testcase, taken from one of the new WPT failures that we hit with the WPT changes that I'm making in bug 1940367.

EXPECTED RESULTS: the four pink bars should all have the same size/position.
ACTUAL RESULTS: the second pink bar isn't the right width. The fourth pink bar isn't at the right position.

The bars that we get wrong have margin-bottom:20px, which shouldn't influence their horizontal sizing or positioning, but currently it does (that's the bug).

Comment 2

[Daniel Holbert [:dholbert]]

Note, for the pink bars in the upper part of the testcase to render, you need to toggle layout.css.stretch-size-keyword.enabled to true in about:config. (And in Chrome, you need to visit chrome://flags to enable experimental web platform features.)

This isn't specifically a bug with stretch, though; the 3rd and 4th boxes in this testcase (which should render the same) demonstrate that we've got a version the same issue with just LengthPercentage sizes as well.