Streaming compilation started the compilation of a module at the
beginning of the code section. However, there exist valid modules which
do not contain a code section. In this CL we check for the existence of
a code section when we finish the stream. We do this by checking if the
module compiler in the AsyncCompileJob exists, because the module
compiler gets initialized at the beginning of the code section.

If we detect that compilation has not been started because there was no
code section, then we start compilation when the stream finishes.

R=clemensh@chromium.org

Bug: chromium:771973
Change-Id: I7c95a7a791d02254f086961e7cd81885eec27382
Reviewed-on: https://chromium-review.googlesource.com/778541
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49494}