Update expectations for instance creations to match front_end.

pkg/front_end/testcases/inference/constructors_downwards_with_constraint.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 {}
 
 class B extends A {}
 
 class Foo<T extends A> {}
 
 void main() {
-  Foo<B> foo = /*@typeArgs=B*/ new Foo();
+  Foo<B> foo = new /*@typeArgs=B*/ Foo();
 }