[v8] Fix uses of deprecated Object::Set in zircon

Always use the Context variant of Set and check its return value. Also
converts ToChecked() cases where the value is not actually examined to
use Check().

Bug: v8:7283
Change-Id: I427df9de56c46882b70d2f5cb8b04623b1dcc176
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1578562
Auto-Submit: Dan Elphick <delphick@chromium.org>
Reviewed-by: Wez <wez@chromium.org>
Commit-Queue: Dan Elphick <delphick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#653952}
1 file changed