Remove V8_ALLOW_ACCESS_TO_RAW_HANDLE_CONSTRUCTOR.

The usage of this define has been obsoleted by removal of UnsafePersistent
from Chromium.

Depends on https://codereview.chromium.org/230613005

R=dcarney@chromium.org
BUG=276323
LOG=N

Review URL: https://codereview.chromium.org/230443004

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@20656 ce2b1a6d-e550-0410-aec6-3dcde31c8c00