Advance html5lib to newest breaking changes in core: getKeys -> keys, etc

test/parser_test.dart

 library parser_test;
 
 import 'dart:io';
 import 'package:unittest/unittest.dart';
 import 'package:unittest/vm_config.dart';
 import 'package:html5lib/dom.dart';
 import 'package:html5lib/parser.dart';
 import 'package:html5lib/src/constants.dart';
 import 'package:html5lib/src/tokenizer.dart';
 import 'package:html5lib/src/utils.dart';
@@ skipping 65 matching lines @@
         int index = 0;
         for (var testData in tests) {
           var input = testData['data'];
           var errors = testData['errors'];
           var innerHTML = testData['document-fragment'];
           var expected = testData['document'];
           if (errors != null) {
             errors = errors.split("\n");
           }
 
-          for (var treeCtor in treeTypes.getValues()) {
+          for (var treeCtor in treeTypes.values) {
             for (var namespaceHTMLElements in const [false, true]) {
               test(input, () {
                 runParserTest(testName, innerHTML, input, expected, errors,
                     treeCtor, namespaceHTMLElements);
               });
             }
           }
 
           index++;
         }
       });
     }
   });
 }