This updates the fast path check in RegExp.p.test reduction to
trigger with constant field tracking.

Bug: v8:8361
Change-Id: I05d2c44189d0cc647b898599d519c2af1d78487f
Reviewed-on: https://chromium-review.googlesource.com/c/1340250Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Jaroslav Sevcik <jarin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57596}