Return the result of the operation in ServiceObject.reload (#14755)

packages/flutter_tools/lib/src/vmservice.dart

diff --git a/packages/flutter_tools/lib/src/vmservice.dart b/packages/flutter_tools/lib/src/vmservice.dart
index 1f803b1..78cef76 100644
--- a/packages/flutter_tools/lib/src/vmservice.dart
+++ b/packages/flutter_tools/lib/src/vmservice.dart
@@ -427,6 +427,7 @@
         completer.completeError(e, st);
       }
       _inProgressReload = null;
+      return await completer.future;
     }
 
     return await _inProgressReload;