This changes the use of "sane" to "sensible" or "valid". I tried to be
sensible in my choice of replacement, by trying to read the comments or
code to see which word matches the intention closest.

Referenced
https://fuchsia.dev/fuchsia-src/contribute/best-practices/respectful_code?hl=en#what_are_examples_of_terminology_to_be_avoided.

Bug: v8:10619
Change-Id: Id957b2e6ff11e95270e1372005e1006d8cf1008d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2254483
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68471}