remove 'the' typo

Closes #60630

GitOrigin-RevId: 7bc7c3d
Change-Id: Ic33a3c7384a55cb70c6333d59acffe75a070a31f
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/424900
Reviewed-by: Kevin Moore <[email protected]>
Commit-Queue: Kevin Moore <[email protected]>

Author: AbdeMohlbi

sdk/lib/async/stream.dart

@@ -1611,7 +1611,7 @@ abstract mixin class Stream<T> {
   /// If [equals] throws, the data event is replaced by an error event
   /// containing the thrown error. The behavior is equivalent to the
   /// original stream emitting the error event, and it doesn't change
-  /// the what the most recently emitted data event is.
+  /// what the most recently emitted data event is.
   ///
   /// The returned stream is a broadcast stream if this stream is.
   /// If a broadcast stream is listened to more than once, each subscription