Allow error-recovery in top-level nodes.

dart/frog/leg/scanner/listener.dart

Index: dart/frog/leg/scanner/listener.dart
diff --git a/dart/frog/leg/scanner/listener.dart b/dart/frog/leg/scanner/listener.dart
index 377ed43cb183be400d3b64f304af70cf67be0b6e..6ee22a7b1cdb846b5806aa6726b4aa5bda22dfc6 100644
--- a/dart/frog/leg/scanner/listener.dart
+++ b/dart/frog/leg/scanner/listener.dart
@@ -480,6 +480,10 @@ class BodyListener extends ElementListener {
     pushNode(new Throw(null, throwToken, endToken));
   }
 
+  void handleNoType(Token token) {
+    pushNode(null);
+  }
+
   NodeList makeNodeList(int count, Token beginToken, Token endToken,
                         String delimiter) {
     Link<Node> nodes = const EmptyLink<Node>();