Instead of conditionally normalizing file paths, go back to using
the basename in the dynamically-generated regular expression
pattern.

Bug: v8:7950, v8:9395, v8:9406
Change-Id: I57d2449a8229a67b038c7fcffe36218848d9a575
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1681122Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Reviewed-by: Tamer Tas <tmrts@chromium.org>
Commit-Queue: Mathias Bynens <mathias@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62439}