Non-overlay scrollbars cause misalignment between tracing markers and thread stack graphs

[mstange]

If you have enough threads that the thread list becomes scrollable, the scrollbar that appears will reduce the space available for the thread graph, which will cause the thread graph to shrink. We don't shrink the tracing markers / jank markers view, so as a result, the two are misaligned.

Example profile: https://perfht.ml/2qjOFiy

[dholbert]

Here's another profile where I'm seeing this: https://perf-html.io/public/2695ee9d3dda4325fbc79993bac934793eb7acda/calltree/?hiddenThreads=&search=resolvestylefor&thread=5&threadOrder=0-2-3-4-5-1

Most of the dark blue marker-bars there are for restyles, which should be aligned with the samples shown in the thread graphs. The misalignment is particularly visible on the 4th & 5th from the end blue marker-bars, particularly if you click the bar to select just that marked region, as shown in my screenshot below:

[julienw]

Since we integrated the markers into the thread lines, the markers are properly aligned. But the selection UI is still off.

I think this is the same bug as https://github.com/devtools-html/perf.html/issues/619 though.

[gregtatum]

Closing in favor of #619