Attempting to make a Vector of an incomplete pointer type would trigger an error as the `CanReinterpretSlice` trail magic is wanting to know the base types, which isn't known yet.
Split `CanReinterpretSlice` into class specializations, where the common case of no-cast doesn't look at the base types.
Change-Id: Id016b027b131f7988ccf3cae93622dacb7802a1d
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/98140
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Dan Sinclair <dsinclair@chromium.org>
Commit-Queue: Ben Clayton <bclayton@google.com>
81f0686523