Selecting a single script from related events was not implemented.

Change-Id: Id6dbe7f8eb235c5917e48a9ade7347404c114618
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2859943Reviewed-by: Sathya Gunasekaran  <gsathya@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74281}