Make sure the other backends ICE on unrecognized attributes.
Add E2E tests, currently skipped for the other backends.
Bug: tint:772
Change-Id: I4e68d111ff79b19ebb6c574058a91debcb746011
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/57642
Commit-Queue: Ben Clayton <bclayton@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
James Price