Was removed from the spec in version 0.99.

Bug: b/126873455
Change-Id: I93c60b7d1e8332e70f7116636384f4f85ea542cb
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/28708Tested-by: Ben Clayton <bclayton@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>