The data from UseCounters are in--V8's custom Promise methods are not
in wide use on the web (<.002%). Therefore, this patch removes them.
That includes:
- Promise.prototype.chain
- Promise.defer -- the most widely used of the bunch
- Promise.accept

For now, those methods are still available by checking the "disable
latest stable JavaScript features" flag, or --promise-extra at the
command line, but I expect them to be fully removable.

R=adamk
CC=rossberg
BUG=v8:3238,v8:4633

Review-Url: https://codereview.chromium.org/1965183002
Cr-Commit-Position: refs/heads/master@{#36152}