Fix typo in wasm_types.dart

Closes #50555

GitOrigin-RevId: 5bdce7c
Change-Id: I0267dc19610746323abab067b1957e9ca32ad61c
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/272340
Reviewed-by: Michael Thomsen <[email protected]>

Author: Coaspe

sdk/lib/wasm/wasm_types.dart

@@ -4,7 +4,7 @@
 
 library dart.wasm;
 
-// A collection a special Dart tytpes that are mapped directly to Wasm types
+// A collection a special Dart types that are mapped directly to Wasm types
 // by the dart2wasm compiler. These types have a number of constraints:
 //
 // - They can only be used directly as types of local variables, fields, or