Update bug number for UseChickenEggHacks

This comment previously referred to a bug that's already been marked as fixed.
The new bug is dedicated to this issue. Turns out we're pretty close.

NOTRY=true
TBR=chrishtr@chromium.org
BUG=383191

Review URL: https://codereview.chromium.org/327143002

git-svn-id: svn://svn.chromium.org/blink/trunk@175935 bbb929c8-8fbe-4397-9dbb-9b2b20218538