The existing signature is problematic for two reasons:

1. The void* -> V cast is invalid if sizeof(V) < sizeof(void*)
2. It's impossible to distinguish between a returned value of 0 and
   nullptr, designating failure.

Bug: v8:6666
Change-Id: I71e8fc9119256c24a15b5bb73438f024f1af4f88
Reviewed-on: https://chromium-review.googlesource.com/1018466Reviewed-by: Peter Marshall <petermarshall@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52708}