Chase imports in analyzer's front_end_inference_test.

pkg/front_end/testcases/inference/infer_from_variables_in_non_cycle_imports_with_flag2.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;
 
 import 'infer_from_variables_in_non_cycle_imports_with_flag2_a.dart';
 
 class B {
-  static var /*@topType=dynamic*/ y = A.x;
+  static var /*@topType=int*/ y = A.x;
 }
 
 test1() {
   A.x = /*error:INVALID_ASSIGNMENT*/ "hi";
   B.y = /*error:INVALID_ASSIGNMENT*/ "hi";
 }
+
+main() {}