Move Rectangle and Point into dart:math.

tests/html/element_test.dart

 // Copyright (c) 2011, 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 ElementTest;
 import '../../pkg/unittest/lib/unittest.dart';
 import '../../pkg/unittest/lib/html_individual_config.dart';
 import 'dart:async';
 import 'dart:html';
 import 'dart:svg' as svg;
 import 'utils.dart';
 
-expectLargeRect(Rect rect) {
+expectLargeRect(Rectangle rect) {
   expect(rect.top, 0);
   expect(rect.left, 0);
   expect(rect.width, greaterThan(100));
   expect(rect.height, greaterThan(100));
   expect(rect.bottom, rect.top + rect.height);
   expect(rect.right, rect.left + rect.width);
 }
 
 void testUnsupported(String name, void f()) {
   test(name, () {
@@ skipping 871 matching lines @@
 
     test('sublist', () {
       var range = makeElementList().sublist(1, 3);
       expect(range.length, 2);
       expect(range[0], isBRElement);
       expect(range[1], isBRElement);
     });
 
   });
 }