... and verify that upper 32-bits of on-heap tagged values contain zero.

This CL also removes scratch register argument from decompression
snippets.

Bug: v8:7703
Change-Id: Ia69d1c5de423c465735719ed07d92df03d9db97c
Reviewed-on: https://chromium-review.googlesource.com/c/1460953
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59634}