Add dart_core.js (fixes #89)

lib/src/dependency_graph.dart

 // Copyright (c) 2015, 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.
 
 /// Tracks the shape of the import/export graph and dependencies between files.
 library dev_compiler.src.dependency_graph;
 
 import 'dart:collection' show HashSet;
 
 import 'package:analyzer/analyzer.dart' show parseDirectives;
@@ skipping 116 matching lines @@
   Iterable<SourceNode> get allDeps => [scripts, runtimeDeps].expand((e) => e);
 
   @override
   Iterable<SourceNode> get depsWithoutParts => allDeps;
 
   /// Parsed document, updated whenever [update] is invoked.
   Document document;
 
   HtmlSourceNode(uri, source, graph) : super(uri, source) {
     var prefix = 'package:dev_compiler/runtime';
-    var files = ['harmony_feature_check.js', 'dart_runtime.js'];
+    var files = ['harmony_feature_check.js', 'dart_runtime.js', 'dart_core.js'];
     if (graph._options.serverMode) {
       files.addAll(const ['messages_widget.js', 'messages.css']);
     }
     files.forEach((file) {
       runtimeDeps.add(graph.nodeFromUri(Uri.parse('$prefix/$file')));
     });
   }
 
   void update(SourceGraph graph) {
     super.update(graph);
@@ skipping 260 matching lines @@
   helper(start);
 }
 
 bool _same(Set a, Set b) => a.length == b.length && a.containsAll(b);
 
 /// An error message discovered while parsing the dependencies between files.
 class DependencyGraphError extends MessageWithSpan {
   const DependencyGraphError(String message, SourceSpan span)
       : super(message, Level.SEVERE, span);
 }