This patch moves the has_braces_ bool to the bit_field_, and moves
function_literal_id_ into the freed-up slack space. This saves
4 bytes on 32-bit platforms and 8 bytes on 64-bit.

Change-Id: Ib5ba475915e46494c75019cfc184aafe72f6407f
Reviewed-on: https://chromium-review.googlesource.com/947467Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Commit-Queue: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51742}