The set of registers used for Pop/PushCallerSaved is a superset of the
ABI caller-saved registers. In the past it may have been the case that
these extra registers had to be saved, but at this point
Pop/PushCallerSaved is only used for fast C calls from JS, so we can
rely on the C-compiled functions saving callee-saved registers
correctly, and only save ABI-required registers ourselves.

Change-Id: I2a172bdbb381a1485654e54e3561d695b6672ed0
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3735130
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/main@{#81467}