Implement support for property accessors

pkg/kernel/testcases/interpreter/object_property_access.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.
+
+library object_property_access_test;
+
+main() {
+  var a1 = new A();
+  print(a1.a);
+  print(a1.b);
+
+  a1.a = 3;
+  print(a1.doubleA);
+
+  var a2 = new A.withArgs(1, 2);
+  print(a2.a);
+  print(a2.b);
+
+  print(a2.doubleA);
+  a2.setA = 42;
+  print(a2.a);
+}
+
+class A {
+  int a;
+  int b = 42;
+
+  A();
+  A.withArgs(this.a, this.b);
+
+  int get doubleA => a + a;
+
+  void set setA(int a) {
+    this.a = a;
+  }
+}