- Add WeakMapPrototypeDelete and WeakSetPrototypeDelete TFJ builtins
  - Fast paths when it's not necessary to shrink the table
- Add WeakCollectionDelete TFS

Some quick benchmarks shows 1.4x - 2.15x gains in performance.
https://github.com/peterwmwong/v8-perf/blob/master/weakcollection-delete/README.md

Bug: v8:5049, v8:6604
Change-Id: I14036df153f3a0242f9083d751658b868b16660a
Reviewed-on: https://chromium-review.googlesource.com/743864Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49076}