This changes the names of the builtins on the Promise.prototype to match
the general naming convention and make it easier to tell what the
builtin is about just by looking at its name.

Bug: v8:7253
Change-Id: I906cc6fc14a6b9d8ffe9c0dcfd94b50439c4cfcf
Reviewed-on: https://chromium-review.googlesource.com/850698Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50367}