Prepare TimelineUIUtils.js for asynchronous source mapping
Prepare TimelineUIUtils.js for asynchronous source mapping

Straight-forward CL that adds {async}/{await}s to various call-sites
in TimelineUIUtils.js.

R=17a2cbc4e33156874a9862b0f530521117e66a3d@chromium.org

Bug: chromium:1032016
Change-Id: I1fac44fe5616fa3f34276b8a7d70d2dd058bb281
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/2071875
Reviewed-by: Mathias Bynens <17a2cbc4e33156874a9862b0f530521117e66a3d@chromium.org>
Commit-Queue: Simon Zünd <38944668e9e2ca98ccd0275b53370f90fa55c113@chromium.org>

ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend