- avoid endless recursion with corrupted traces
- speed up page by async bar repainting
- minor tweaks to avoid unnecessary work
- move helper functions to make command line version parse log files

Change-Id: If8ce9cc4093030d648fbc7bbb60e53412e9f7a79
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2115434
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Sathya Gunasekaran  <gsathya@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66942}