This allows them to be fully defined before being referenced, which
fixes compile errors in C++20.
Bug: chromium:1284275
Change-Id: I3c0f874406247c04d53710431931f82c3deaff3c
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/99080
Reviewed-by: Austin Eng <enga@chromium.org>
Commit-Queue: Peter Kasting <pkasting@google.com>
Auto-Submit: Peter Kasting <pkasting@google.com>