Since the function entry stack check happens outside of the IR, the
standard register spilling mechanisms don't kick in and registers that
expect to be valid might be clobbered.

The only such case is, in fact, the new.target register, so make sure
it is preserved across the stack check.

R=jgruber@chromium.org

Bug: v8:7700
Change-Id: I530b6af882ca188b0e3c7da752f810506f3340a0
Fixed: v8:13226, chromium:1356082
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3852389
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82700}