- don't restore the context register after InvokeFunction unless we need
  to for throwing exceptions.
- manually manage the frame to improve code layout for the fast path

Change-Id: Ibccb3bf604085bd470c4279d0348edcf6f18d796
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2523196
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#71094}