The regexp for finding resources to be pushed to Android devices was
too lax. On empty strings it tried to check for more resources on a
directory and hung.

The last test262 roll contains tests with empty imports that started
hanging in this way.

TBR=neis@chromium.org
NOTRY=true

Bug: v8:7834
Change-Id: Ie58f1b18bdd99b7b40c1fb39b25e2f481932e0f3
Reviewed-on: https://chromium-review.googlesource.com/c/1270579Reviewed-by: Georg Neis <neis@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56465}