[cleanup] Fix uses of deprecated v8::Object::Set/Get

Replace uses of Get/Set with Context versions that return a
Maybe/MaybeLocal and check their return value mostly using
ToLocalChecked or Check.

Bug: v8:7283, v8:8562
Change-Id: Id8614f6e599cad628f3de8614d5a600d2148eb76
Reviewed-on: https://chromium-review.googlesource.com/c/1449676
Commit-Queue: Dan Elphick <delphick@chromium.org>
Commit-Queue: Kentaro Hara <haraken@chromium.org>
Auto-Submit: Dan Elphick <delphick@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#628313}
3 files changed