Reland after splitting large classes further.

es6/classes.js is large and causes timeouts and OOM on some of the
configurations.

Bug: v8:9246
Change-Id: I51952447eb6a6b46d78410d5d3798292f5a8d87d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1706061
Commit-Queue: Mythri Alle <mythria@chromium.org>
Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62864}