Removed fixed dependencies

packages/html/test/support.dart

 /// Support code for the tests in this directory.
 library support;
 
 import 'dart:io';
 import 'dart:collection';
 import 'package:path/path.dart' as path;
 import 'package:html/src/treebuilder.dart';
 import 'package:html/dom.dart';
 import 'package:html/dom_parsing.dart';
 
 typedef TreeBuilder TreeBuilderFactory(bool namespaceHTMLElements);
 
-Map _treeTypes;
+Map<String, TreeBuilderFactory> _treeTypes;
 Map<String, TreeBuilderFactory> get treeTypes {
   if (_treeTypes == null) {
     // TODO(jmesserly): add DOM here once it's implemented
     _treeTypes = {"simpletree": (useNs) => new TreeBuilder(useNs)};
   }
   return _treeTypes;
 }
 
 final testDataDir = Platform.script.resolve('data').toFilePath();
 
@@ skipping 102 matching lines @@
     _str.write(node);
     visitChildren(node);
   }
 
   visitChildren(Node node) {
     indent += 2;
     for (var child in node.nodes) visit(child);
     indent -= 2;
   }
 
-  visitDocument(node) {
+  visitDocument(node) => _visitDocumentOrFragment(node);
+
+  _visitDocumentOrFragment(node) {
     indent += 1;
     for (var child in node.nodes) visit(child);
     indent -= 1;
   }
 
-  visitDocumentFragment(DocumentFragment node) => visitDocument(node);
+  visitDocumentFragment(DocumentFragment node) =>
+      _visitDocumentOrFragment(node);
 
   visitElement(Element node) {
     _newline();
     _str.write(node);
     if (node.attributes.length > 0) {
       indent += 2;
       var keys = new List.from(node.attributes.keys);
       keys.sort((x, y) => x.compareTo(y));
       for (var key in keys) {
         var v = node.attributes[key];
         if (key is AttributeName) {
           AttributeName attr = key;
           key = "${attr.prefix} ${attr.name}";
         }
         _newline();
         _str.write('$key="$v"');
       }
       indent -= 2;
     }
     visitChildren(node);
   }
 }