Added D3D12Error to check HRESULTS and return error messages
with the correct error names.
Remove ASSERT_SUCCESS from D3D12 backend and use
MaybeError and ResultError instead to handle errors.
Bug: dawn:19
Change-Id: Idf2f1987725e7e658bd29a9b13653125ab43c564
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/12000
Reviewed-by: Rafael Cintron <rafael.cintron@microsoft.com>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Natasha Lee