We never read this pointer, and it could cause crashes when the GC
inspects it.

Bug: v8:6956
Change-Id: Ib493c2f0418de3e89975fd1f5a7e86cc66868ec7
Reviewed-on: https://chromium-review.googlesource.com/725331Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Peter Marshall <petermarshall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48681}