We already cleanup these scripts on frontend side. It is crucial to
cleanup them on backend side as well, since some web applications use
following logic: get some data from network, add this data to buffer,
try to parse buffer using JSON.parse. On each unsuccessfull JSON.parse
we get another scriptFailedToParse event.

Frontend logic of discarding scripts: https://goo.gl/FDtaWK

Some idea of smarter logic here: track what script ids are reported
using protocol and cleanup only script ids which reported not only as
part of scriptFailedToParse event.

R=alph@chromium.org

Bug: chromium:810812
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel
Change-Id: Ifd67764c232e4abc7dc6e8e69a651bf9ac0e381b
Reviewed-on: https://chromium-review.googlesource.com/919834
Commit-Queue: Aleksey Kozyatinskiy <kozyatinskiy@chromium.org>
Reviewed-by: Alexei Filippov <alph@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51337}