Fix annotation of generic method invocations in Fasta inference tests (again).

pkg/front_end/testcases/inference/future_then_explicit_future.dart

Index: pkg/front_end/testcases/inference/future_then_explicit_future.dart
diff --git a/pkg/front_end/testcases/inference/future_then_explicit_future.dart b/pkg/front_end/testcases/inference/future_then_explicit_future.dart
index 8006aa19df888e80976220ff1b69ba36caab27ef..6f49c38ddfe1f4bb8099130249ca764e9d7ed6f0 100644
--- a/pkg/front_end/testcases/inference/future_then_explicit_future.dart
+++ b/pkg/front_end/testcases/inference/future_then_explicit_future.dart
@@ -9,17 +9,16 @@ import "dart:async";
 
 m1() {
   Future<int> f;
-  var /*@type=Future<List<int>>*/ x = /*@promotedType=none*/ f
-      . /*@typeArgs=Future<List<int>>*/ then<Future<List<int>>>(
-          /*error:ARGUMENT_TYPE_NOT_ASSIGNABLE*/
-          /*@returnType=List<dynamic>*/ (/*@type=int*/ x) => /*@typeArgs=dynamic*/ []);
+  var /*@type=Future<List<int>>*/ x = /*@promotedType=none*/ f.then<
+          Future<List<int>>>(
+      /*error:ARGUMENT_TYPE_NOT_ASSIGNABLE*/
+      /*@returnType=List<dynamic>*/ (/*@type=int*/ x) => /*@typeArgs=dynamic*/ []);
   Future<List<int>> y = /*@promotedType=none*/ x;
 }
 
 m2() {
   Future<int> f;
-  var /*@type=Future<List<int>>*/ x = /*@promotedType=none*/ f
-      . /*@typeArgs=List<int>*/ then<List<int>>(
-          /*@returnType=List<int>*/ (/*@type=int*/ x) => /*@typeArgs=int*/ []);
+  var /*@type=Future<List<int>>*/ x = /*@promotedType=none*/ f.then<List<int>>(
+      /*@returnType=List<int>*/ (/*@type=int*/ x) => /*@typeArgs=int*/ []);
   Future<List<int>> y = /*@promotedType=none*/ x;
 }