noexcept keyword needs to be consistent between the declaration and
implementation in C++17.

Bug: v8:8616, chromium:752720
Change-Id: Iff4022c8c4b861ebdbe8e08995af1bc4da866dae
Reviewed-on: https://chromium-review.googlesource.com/c/1396459Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Taiju Tsuiki <tzik@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58609}