We want to limit these cases since they result in unecessary work on background threads
doing the streaming parse / compile, and delay the script execution unecessarily
while waiting for the streamer to complete.

BUG=chromium:865098

Change-Id: Ibb3346c2e644bb333521d876d00aeb9cc063b6aa
Reviewed-on: https://chromium-review.googlesource.com/1163669Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#54929}