Drive-by-fix:
- Show tooltips in list-panel entries
- Use fixed kChunkWidth in timeline-track

Bug: v8:10644
Change-Id: I738f613c9a35726b9ab4a6c51f784638eade9335
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2867467
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Patrick Thier <pthier@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74356}