IsCompleted is backwards. For a more consistent api, the function is
renamed IsActive and logic is flipped.
Following up on https://chromium-review.googlesource.com/c/v8/v8/+/2461840
The intend is to make the distinction between IsActive and IsValid obvious.

Change-Id: Iaf00b9f6ffa8f1efe93ae29f09899737ef20f04d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2510969Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Etienne Pierre-Doray <etiennep@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70901}