Do not round the clipping region with mixed overflow clip

[chromium-wpt-export-bot]

The CSSWG resolved [1] to not apply rounded border clipping when one of
overflow-x or overflow-y computes to clip and the other computes to
visible (https://drafts.csswg.org/css-overflow/#corner-clipping). This
patch updates our implementation to not create the inner border radius
clip in this mixed clip/visible scenario.

[1] w3c/csswg-drafts#7434

Bug: 1416649
Change-Id: I4d24ac82ecdafba5fa691efb1ce85892c734c717
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5171405
Reviewed-by: David Baron <[email protected]>
Commit-Queue: Philip Rogers <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1243240}

[wpt-pr-bot]

The review process for this patch is being conducted in the Chromium project.