The AsyncCompileJob should not cancel compilation if baseline
compilation already finished. At that point, we might still be tiering
up, and the module might even already be shared across isolates.

R=titzer@chromium.org
CC=ahaas@chromium.org

Bug: v8:8677, v8:8689
Change-Id: Ia2192a1985bf4a3b7125ce5a713c83bbcc1bf6b7
Reviewed-on: https://chromium-review.googlesource.com/c/1417931
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58916}