Fix NPE in parser.

dart/frog/leg/scanner/parser.dart

Index: dart/frog/leg/scanner/parser.dart
diff --git a/dart/frog/leg/scanner/parser.dart b/dart/frog/leg/scanner/parser.dart
index f2427bcb21a2508ed5b0fdb59749ba74d6ad655e..af9cc7c50a27565a180b1ec4f7da0239f835f145 100644
--- a/dart/frog/leg/scanner/parser.dart
+++ b/dart/frog/leg/scanner/parser.dart
@@ -317,7 +317,9 @@ class Parser {
   Token parseTypeVariablesOpt(Token token) {
     if (optional('<', token)) {
       BeginGroupToken beginGroupToken = token;
-      token = beginGroupToken.endGroup.next;
+      if (beginGroupToken.endGroup !== null) {

[ngeoffray, 2012/02/07 13:40:27]

Please add a comment that you're considering the following tokens as not being
part of the type variables.

[ahe, 2012/02/07 14:24:47]

Done.

+        token = beginGroupToken.endGroup.next;
+      }
     }
     listener.handleNoTypeVariables(token);
     return token;