Refactor runtime into libraries, better type reps

lib/src/codegen/html_codegen.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.
 
 library dev_compiler.src.codegen.html_codegen;
 
 import 'package:html/dom.dart';
 import 'package:html/parser.dart' show parseFragment;
 import 'package:logging/logging.dart' show Logger;
 import 'package:path/path.dart' as path;
@@ skipping 86 matching lines @@
 /// A script tag that loads the .js code for a compiled library.
 Node _libraryInclude(String jsUrl) =>
     parseFragment('<script src="$jsUrl"></script>\n');
 
 /// A script tag that invokes the main function on the entry point library.
 Node _invokeMain(String mainLibraryName) {
   var code = mainLibraryName == null
       ? 'console.error("dev_compiler error: main was not generated");'
       // TODO(vsm): Can we simplify this?
       // See: https://github.com/dart-lang/dev_compiler/issues/164
-      : "dart.start('$mainLibraryName');";
+      : "loader.start('$mainLibraryName');";
   return parseFragment('<script>$code</script>\n');
 }
 
 /// Convert the outputPath to include the hash in it. This function is the
 /// reverse of what the server does to determine whether a request needs to have
 /// cache headers added to it.
 _addHash(String outPath, String hash) {
   // (the ____ prefix makes it look better in the web inspector)
   return '$outPath?____cached=$hash';
 }
 
 final _log = new Logger('dev_compiler.src.codegen.html_codegen');