Fixing a number of dart:html analyzer issues

tests/html/element_test.dart

Index: tests/html/element_test.dart
diff --git a/tests/html/element_test.dart b/tests/html/element_test.dart
index a255c6856dd79aeea94268b16aef0727a9e13fef..d9fa2a66ea65045884f061f0cf97b4bf3905112c 100644
--- a/tests/html/element_test.dart
+++ b/tests/html/element_test.dart
@@ -439,12 +439,6 @@ main() {
       expect(el.children.last, isHRElement);
     });
 
-    test('addLast', () {
-      var el = makeElement();
-      el.children.addLast(new Element.tag('hr'));
-      expect(el.children.last, isHRElement);
-    });
-
     test('iterator', () {
       var els = [];
       var el = makeElementWithChildren();
@@ -594,8 +588,6 @@ main() {
 
     testUnsupported('[]=', () => getQueryAll()[1] = new Element.tag('br'));
     testUnsupported('add', () => getQueryAll().add(new Element.tag('br')));
-    testUnsupported('addLast', () =>
-        getQueryAll().addLast(new Element.tag('br')));
 
     testUnsupported('addAll', () {
       getQueryAll().addAll([