Fix annotation of generic method invocations in Fasta inference tests.

pkg/front_end/testcases/inference/generic_methods_inference_error.dart

 // Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /*@testedFeatures=inference*/
 library test;
 
 main() {
   List<String> y;
-  Iterable<String> x = /*@promotedType=none*/ y.map(
+  Iterable<String> x = /*@promotedType=none*/ y. /*@typeArgs=String*/ map(
       /*error:ARGUMENT_TYPE_NOT_ASSIGNABLE*/ /*@returnType=double*/ (String
               z) =>
           1.0);
 }