Migrated test block 216 to Dart 2.0.

tests/lib_2/math/point_test.dart

 // Copyright (c) 2013, 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.
 
 import 'dart:math';
 import 'package:expect/expect.dart';
 
 main() {
   // constructor
   {
@@ skipping 79 matching lines @@
   {
     var a = new Point(5, 10);
     var b = new Point(0, 0);
     Expect.equals(a.distanceTo(b), a.magnitude);
     Expect.equals(0, b.magnitude);
 
     var c = new Point(-5, -10);
     Expect.equals(a.distanceTo(b), c.magnitude);
   }
 }