... so that it can be used during off-thread code assembly.

R=bmeurer@chromium.org

Bug: v8:6048
Change-Id: Iaa9b534b23d02da69c2b2395c1eacfdcffb3ac2f
Reviewed-on: https://chromium-review.googlesource.com/561677Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46455}