Remove TINT_EXPECTS_UBOS_TO_BE_MULTIPLE_OF_16 macro

This was a temporary measure to be able to roll Tint into Dawn with this
change. Dawn's usage of this macro was removed in:
https://dawn-review.googlesource.com/c/dawn/+/58365

Bug: tint:984
Change-Id: Ie6ab047a6398aa1a29b56c3181ec38691f34498d
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/58322
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: Antonio Maiorano <amaiorano@google.com>
diff --git a/include/tint/tint.h b/include/tint/tint.h
index 9d28687..ac1c8b3 100644
--- a/include/tint/tint.h
+++ b/include/tint/tint.h
@@ -59,7 +59,4 @@
 #include "src/writer/hlsl/generator.h"
 #endif  // TINT_BUILD_HLSL_WRITER
 
-// TODO(crbug/984): Remove once Dawn builds with this flag
-#define TINT_EXPECTS_UBOS_TO_BE_MULTIPLE_OF_16
-
 #endif  // INCLUDE_TINT_TINT_H_