Implement type inference for PropertySet.

pkg/front_end/testcases/inference/constructors_infer_from_arguments.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 C<T> {
   T t;
   C(this.t);
 }
 
 main() {
   var /*@type=C<int>*/ x = new /*@typeArgs=int*/ C(42);
 
   num y;
   C<int> c_int = new /*@typeArgs=int*/ C(
       /*info:DOWN_CAST_IMPLICIT*/ y);
 
   // These hints are not reported because we resolve with a null error listener.
   C<num> c_num = new /*@typeArgs=num*/ C(123);
-  C<num> c_num2 = (new /*@typeArgs=num*/ C(456))..t = 1.0;
+  C<num> c_num2 = (new /*@typeArgs=num*/ C(456)).. /*@target=C::t*/ t = 1.0;
 
   // Down't infer from explicit dynamic.
   var /*@type=C<dynamic>*/ c_dynamic = new C<dynamic>(42);
-  x.t = /*error:INVALID_ASSIGNMENT*/ 'hello';
+  x. /*@target=C::t*/ t = /*error:INVALID_ASSIGNMENT*/ 'hello';
 }