[text-box-trim] Add tests for multi-col

[chromium-wpt-export-bot]

The text-box-trim should apply only to the top of the first
fragment and the bottom of the last fragment, resolved at
w3c/csswg-drafts#5335.

This patch adds tests for this, 001 for when the
text-box-trim is applied to the multicol container, and
002 for when a box with text-box-trim is block fragmented
by ancestor multicol.

Bug: 40254880
Change-Id: Ice29f39cbef0c20284edd809942754176a395d23
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5564105
Reviewed-by: Kent Tamura <[email protected]>
Commit-Queue: Kent Tamura <[email protected]>
Auto-Submit: Koji Ishii <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1305545}

[wpt-pr-bot]

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