This CL enhances the fast C API in a way to allow passing the receiver
to the fast callback as Local<Object> instead of Local<Value>. It also
fixes documentation comments.

Bug: chromium:1052746
Change-Id: I424aa83023c2e6633b9df08ee040bf170db32b3d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2887510
Commit-Queue: Maya Lekova <mslekova@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74519}