Fix deprecated V8 function use in V8UnitTest

Fixes use of deprecated Object::Get/Set V8 functions by instead using
the Context version and checking the return values.

Bug: v8:7283, v8:8562
Change-Id: Idf2b5b596a431ad249d9bbcbf8f295537b2bab80
Reviewed-on: https://chromium-review.googlesource.com/c/1452177
Auto-Submit: Dan Elphick <delphick@chromium.org>
Commit-Queue: Jochen Eisinger <jochen@chromium.org>
Reviewed-by: Jochen Eisinger <jochen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#629121}
1 file changed