[gin] Allow posting non-nestable tasks through V8

Will be used to allow V8 posting top-level tasks.

Bug: chromium:843903
Change-Id: I97caa705b561fa8832ef8a11abfc3eefe47ec3f8
Reviewed-on: https://chromium-review.googlesource.com/c/1273140
Reviewed-by: Jochen Eisinger <jochen@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#598802}
4 files changed