In-process capture of exceptions doesn't work well because there's no
symbols on-device. Instead, just let the system crashlogger output a
backtrace that the run script can symbolize.

Bug: chromium:731217
Change-Id: I9a509a29e55229a5d8675c9bdc890b50a6a9bfb9
Reviewed-on: https://chromium-review.googlesource.com/619947
Commit-Queue: Scott Graham <scottmg@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47440}