CL https://chromium-review.googlesource.com/c/v8/v8/+/1660623
("[Turbofan] Brokerize more promise reductions in JSCallReducer")
introduced a bug where we bail out of a call reduction but failed
to remove graph constructs added by the MapInference class.

R=jarin@chromium.org

Bug: chromium:976256, chromium:976524
Change-Id: I97f142fe6c1caba5e679f7df742893536c83b2d8
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1666990Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Michael Stanton <mvstanton@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62267}