add mock unawaited

Change-Id: I3df9342779f95a2e160b56613ab3f31068694a0e
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/236200
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Commit-Queue: Phil Quitslund <pquitslund@google.com>
diff --git a/pkg/analyzer/lib/src/test_utilities/mock_sdk.dart b/pkg/analyzer/lib/src/test_utilities/mock_sdk.dart
index d1cb139..ba0dc02 100644
--- a/pkg/analyzer/lib/src/test_utilities/mock_sdk.dart
+++ b/pkg/analyzer/lib/src/test_utilities/mock_sdk.dart
@@ -71,6 +71,8 @@
   }
   static void run(void callback()) {}
 }
+
+void unawaited(Future<void>? future) {}
 ''',
   ),
   MockSdkLibraryUnit(
diff --git a/pkg/analyzer/test/src/summary/resynthesize_common.dart b/pkg/analyzer/test/src/summary/resynthesize_common.dart
index 26542c5..032c7d8 100644
--- a/pkg/analyzer/test/src/summary/resynthesize_common.dart
+++ b/pkg/analyzer/test/src/summary/resynthesize_common.dart
@@ -19884,6 +19884,7 @@
     StreamSubscription: dart:async;dart:async/stream.dart;StreamSubscription
     StreamTransformer: dart:async;dart:async/stream.dart;StreamTransformer
     Timer: dart:async;Timer
+    unawaited: dart:async;unawaited
 ''',
         withExportScope: true);
   }