Test to cover a lot of injected script source corner cases.

R=dgozman@chromium.org

Bug: chromium:595206
Cq-Include-Trybots: luci.chromium.try:linux_chromium_headless_rel;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: Ia631de58c5a92b39ec3933c56cf7e3f108b9bd9e
Reviewed-on: https://chromium-review.googlesource.com/c/1292688
Commit-Queue: Aleksey Kozyatinskiy <kozyatinskiy@chromium.org>
Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56863}