- Add Map, WeakMap, Set, and WeakSet initial prototype maps to native context.
- Set and WeakSet constructors check whether prototype map differs from initial
  before choosing the fast path.

Bug: chromium:798026
Change-Id: I5f9cc2463f89e17f06a66b565c625fce133d01fb
Reviewed-on: https://chromium-review.googlesource.com/853698
Commit-Queue: Peter Wong <peter.wm.wong@gmail.com>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50691}