Track v8 API changes.

R=jochen@chromium.org, dcarney@chromium.org
BUG=324225

Review URL: https://codereview.chromium.org/124103003

Patch from Sven Panne <svenpanne@chromium.org>.

git-svn-id: svn://svn.chromium.org/blink/trunk@164458 bbb929c8-8fbe-4397-9dbb-9b2b20218538