Add a special builtin performing a ToBoolean operation for jumps in
baseline code, which

   a) returns the original value as the first return value, to avoid
      needing to save it in the caller, and
   b) returns the true/false value as a Smi, to make the baseline-side
      comparison a cheap comparison against zero.

This reduces JumpIfToBoolean (on x64) from ~40 to ~30 bytes.

Bug: v8:11420
Change-Id: Idee51405b1e450cdd11ccb45ed82ddbc9119ae74
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2854654
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Patrick Thier <pthier@chromium.org>
Reviewed-by: Patrick Thier <pthier@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74239}