Update Try Dart to new scanner behavior.

dart/site/try/src/editor.dart

 // Copyright (c) 2013, 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 trydart.editor;
 
 import 'dart:html';
 
-import 'package:compiler/implementation/scanner/scannerlib.dart'
-  show
+import 'package:compiler/implementation/scanner/scannerlib.dart' show
     EOF_TOKEN,
+    ErrorToken,
     StringScanner,
     Token;
 
 import 'ui.dart' show
     currentTheme,
     hackDiv,
     mainEditorPane,
     observer,
     outputDiv;
 
@@ skipping 171 matching lines @@
   var parent = element.parentNode;
   if (parent == null) return;
   for (Node child in new List.from(element.nodes)) {
     child.remove();
     parent.insertBefore(child, element);
   }
   element.remove();
 }
 
 Decoration getDecoration(Token token) {
+  if (token is ErrorToken) {
+    isMalformedInput = true;
+    return new DiagnosticDecoration('error', token.assertionMessage);
+  }
   String tokenValue = token.value;
   String tokenInfo = token.info.value;
   if (tokenInfo == 'string') return currentTheme.string;
   if (tokenInfo == 'identifier') {
     seenIdentifiers.add(tokenValue);
     return CodeCompletionDecoration.from(currentTheme.foreground);
   }
   if (tokenInfo == 'keyword') return currentTheme.keyword;
   if (tokenInfo == 'comment') return currentTheme.singleLineComment;
   if (tokenInfo == 'malformed input') {
     isMalformedInput = true;
     return new DiagnosticDecoration('error', tokenValue);
   }
   return currentTheme.foreground;
 }
 
 diagnostic(text, tip) {
   if (text is String) {
     text = new Text(text);
   }
   return new AnchorElement()
       ..classes.add('diagnostic')
       ..append(text)
       ..append(tip);
 }