Adding tests for Element & Node lists insert method.

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;
@@ skipping 447 matching lines @@
         new Element.tag('h1')
       ]);
       expect(el.children[0], isBRElement);
       expect(el.children[1], isImageElement);
       expect(el.children[2], isInputElement);
       expect(el.children[3], isSpanElement);
       expect(el.children[4], isAnchorElement);
       expect(el.children[5], isHeadingElement);
     });
 
+    test('insert', () {
+      var element = new DivElement();
+      element.children.insert(0, new BRElement());
+      expect(element.children[0], isBRElement);
+      element.children.insert(0, new HRElement());
+      expect(element.children[0], isHRElement);
+      element.children.insert(1, new ImageElement());
+      expect(element.children[1], isImageElement);
+      element.children.insert(element.children.length, new InputElement());
+      expect(element.children.last, isInputElement);
+    });
+
     test('clear', () {
       var el = makeElementWithChildren();
       el.children.clear();
       expect(el.children, equals([]));
     });
 
     test('removeLast', () {
       var el = makeElementWithChildren();
       expect(el.children.removeLast(), isInputElement);
       expect(el.children.length, 2);
@@ skipping 155 matching lines @@
     });
 
     test('getRange', () {
       var range = makeElList().getRange(1, 2);
       expect(range, isElementList);
       expect(range[0], isImageElement);
       expect(range[1], isInputElement);
     });
   });
 }