This should help to keep syntax errors from creeping into v8.h

Also, I'll remove usages of to-be-deprecated APIs and turn this flag on
for standalone builds

BUG=4134
R=vogelheim@chromium.org
LOG=n

Review URL: https://codereview.chromium.org/1149633003

Cr-Commit-Position: refs/heads/master@{#28538}