We now keep the same percentage of the window occupied by the panel
when toggling Maximize (both maximizing, or un-maximizing). This
also means that it no longer forces the side panels open when
toggling maximizing.

Also took the opportunity and cleaned up names and resizer.ts.

Bug: v8:7327
Change-Id: I60b574a833f3059e447aa17fae8a687d32ac29d5
Notry: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1903970Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Commit-Queue: Santiago Aboy Solanes <solanes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65085}