Fix annotation of generic method invocations in Fasta inference tests.

pkg/front_end/testcases/inference/future_or_subtyping.dart

Index: pkg/front_end/testcases/inference/future_or_subtyping.dart
diff --git a/pkg/front_end/testcases/inference/future_or_subtyping.dart b/pkg/front_end/testcases/inference/future_or_subtyping.dart
index 349251b0b1225a0aa256062ddb5052af1505379e..23d27b60e8c000da8c67a6a8432d801a86ac5b6c 100644
--- a/pkg/front_end/testcases/inference/future_or_subtyping.dart
+++ b/pkg/front_end/testcases/inference/future_or_subtyping.dart
@@ -11,6 +11,8 @@ void add(int x) {}
 add2(int y) {}
 main() {
   Future<int> f;
-  var /*@type=Future<void>*/ a = /*@promotedType=none*/ f.then(add);
-  var /*@type=Future<dynamic>*/ b = /*@promotedType=none*/ f.then(add2);
+  var /*@type=Future<void>*/ a = /*@promotedType=none*/ f
+      . /*@typeArgs=void*/ then(add);
+  var /*@type=Future<dynamic>*/ b = /*@promotedType=none*/ f
+      . /*@typeArgs=dynamic*/ then(add2);
 }