Get rid of promotedType=none annotations

pkg/front_end/testcases/inference/propagate_inference_transitively.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;
 
 class A {
   int x = 2;
 }
 
 test5() {
   var /*@type=A*/ a1 = new A();
-  /*@promotedType=none*/ a1.x = /*error:INVALID_ASSIGNMENT*/ "hi";
+  a1.x = /*error:INVALID_ASSIGNMENT*/ "hi";
 
   A a2 = new A();
-  /*@promotedType=none*/ a2.x = /*error:INVALID_ASSIGNMENT*/ "hi";
+  a2.x = /*error:INVALID_ASSIGNMENT*/ "hi";
 }