In C++17 noexcept becomes part of the type system and thus needs to be
consistently applied between function declarations and definitions.

Change-Id: Ia34faa9d9d1f18916655fd5a1a8ec9f6b414f1e9
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2643391Reviewed-by: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Jan Wilken Dörrie <jdoerrie@chromium.org>
Cr-Commit-Position: refs/heads/master@{#72255}