Unify PokeCSP/JSSP and ClaimCSP/JSSP, remove RestoreJSSP/CSP, and
remove UseNativeStack.

Bug: v8:6644
Change-Id: I482237a0e112f986c6155dce253749f55bd08f5f
Reviewed-on: https://chromium-review.googlesource.com/860104Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Martyn Capewell <martyn.capewell@arm.com>
Cr-Commit-Position: refs/heads/master@{#50531}