cleanup unnecessary nullaware op on an extension on a nullable


```
extension<T> on T? {
  R? mapOrNull<R>(R Function(T) mapper) {
    final self = this;
    return self != null ? mapper(self) : null;
  }
}
```



Change-Id: I9276257423df85aabc3f30e6f5ea817fad92ce6a
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/245440
Commit-Queue: Phil Quitslund <pquitslund@google.com>
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
diff --git a/pkg/analyzer/lib/src/summary2/macro_declarations.dart b/pkg/analyzer/lib/src/summary2/macro_declarations.dart
index 569b47c..2a097a8 100644
--- a/pkg/analyzer/lib/src/summary2/macro_declarations.dart
+++ b/pkg/analyzer/lib/src/summary2/macro_declarations.dart
@@ -261,7 +261,7 @@
     return macro.TypeParameterDeclarationImpl(
       id: macro.RemoteInstance.uniqueId,
       identifier: _identifier(node.name),
-      bound: node.bound?.mapOrNull(_typeAnnotation),
+      bound: node.bound.mapOrNull(_typeAnnotation),
     );
   }