Enable top level inference of instance property gets/sets.

pkg/front_end/testcases/inference_new/property_get_toplevel.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 {
   int field = 0;
   int get getter => 0;
   int function() => 0;
 }
 
 C c = new C();
-var /*@topType=dynamic*/ field_ref = c. /*@target=C::field*/ field;
-var /*@topType=dynamic*/ getter_ref = c. /*@target=C::getter*/ getter;
+var /*@topType=int*/ field_ref = c. /*@target=C::field*/ field;
+var /*@topType=int*/ getter_ref = c. /*@target=C::getter*/ getter;
 var /*@topType=() -> int*/ function_ref = c. /*@target=C::function*/ function;
-var /*@topType=dynamic*/ field_ref_list = /*@typeArgs=int*/ [
+var /*@topType=List<int>*/ field_ref_list = /*@typeArgs=int*/ [
   c. /*@target=C::field*/ field
 ];
-var /*@topType=dynamic*/ getter_ref_list = /*@typeArgs=int*/ [
+var /*@topType=List<int>*/ getter_ref_list = /*@typeArgs=int*/ [
   c. /*@target=C::getter*/ getter
 ];
 var /*@topType=List<() -> int>*/ function_ref_list = /*@typeArgs=() -> int*/ [
   c. /*@target=C::function*/ function
 ];
 
 main() {}