The handle was always created empty which resulted in a DCHECK crash
in debug builds and in never-cancelled tasks in release builds.

Bug: chromium:1056170
Change-Id: I798ce65c37738bbe9c60b44b692ff04536f6d830
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2388101Reviewed-by: Anton Bikineev <bikineev@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69653}