Don't use (almost) deprecated FunctionTemplate::New version.

R=dcarney@chromium.org
BUG=324225

Review URL: https://codereview.chromium.org/108193002

git-svn-id: svn://svn.chromium.org/blink/trunk@163347 bbb929c8-8fbe-4397-9dbb-9b2b20218538