Update Try Dart to new scanner behavior.

dart/site/try/src/interaction_manager.dart

Index: dart/site/try/src/interaction_manager.dart
diff --git a/dart/site/try/src/interaction_manager.dart b/dart/site/try/src/interaction_manager.dart
index 88986cc35024fe143562b74fc9f58fb2f86cf8c1..a59cf4e43cfb495f0b56d09764cef63247e15366 100644
--- a/dart/site/try/src/interaction_manager.dart
+++ b/dart/site/try/src/interaction_manager.dart
@@ -16,9 +16,10 @@ import 'dart:math' show
 import 'dart:async' show
     Future;
 
-import 'package:compiler/implementation/scanner/scannerlib.dart'
-  show
+import 'package:compiler/implementation/scanner/scannerlib.dart' show
+    BeginGroupToken,
     EOF_TOKEN,
+    ErrorToken,
     StringScanner,
     Token;
 
@@ -685,6 +686,15 @@ void tokenizeAndHighlight(String currentText,
     if (charOffset < offset) continue; // Happens for scanner errors.
 
     Decoration decoration = editor.getDecoration(token);
+
+    Token follow = token.next;
+    if (token is BeginGroupToken) {
+      follow = token.endGroup.next;
+    }
+    if (follow is ErrorToken) {
+      decoration = editor.getDecoration(follow);
+    }
+
     if (decoration == null) continue;
 
     // Add a node for text before current token.