Part 4 - Apply flex item's stretched cross-size when computing flex container's intrinsic inline size.
For flex items with an aspect-ratio, the expectation is that the stretched
cross-sizes can be transferred to the main axis, affecting their intrinsic
inline-size contribution to the flex container's intrinsic inline-size.
Add aspect-ratio-intrinsic-size-008.html (adapted from 003.html) to test a
flex item with border and padding since the existing tests do not cover this.
Differential Revision: https://phabricator.services.mozilla.com/D222050
bugzilla-url: https://bugzilla.mozilla.org/show_bug.cgi?id=1742042
gecko-commit: 426eef56bc22151694e09e68ee40e3b41bace7d2
gecko-reviewers: dholbert