Shared function info marking is now side-effect free, so can be handled
by base HeapVisitor.

Concurrent marker does not bailout on shared function infos.

Bug: chromium:694255
Change-Id: I41efece68f6758219fca318deb97a7f163ee9638
Reviewed-on: https://chromium-review.googlesource.com/608700
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47315}