Diagnose unterminated "grouping" characters.

dart/frog/leg/scanner/scanner_task.dart

Index: dart/frog/leg/scanner/scanner_task.dart
diff --git a/dart/frog/leg/scanner/scanner_task.dart b/dart/frog/leg/scanner/scanner_task.dart
index 27ee7bf82745882fbd07d5a1c5d45737336897f1..b72ad7c6c20227e6f163dc895f44f2505a5739bb 100644
--- a/dart/frog/leg/scanner/scanner_task.dart
+++ b/dart/frog/leg/scanner/scanner_task.dart
@@ -29,14 +29,12 @@ class ScannerTask extends CompilerTask {
     } catch (MalformedInputException ex) {
       Token token;
       var message;
-      if (ex.message is int) {
+      if (ex.position is int) {

[ngeoffray, 2012/01/24 09:12:35]

This seems fragile if we self-host. To make it robust, I would do a 'is num'
check. Or why don't you add the required fields on MalformedInputException?

[ahe, 2012/01/24 09:23:54]

Done. I've also added a TODO to always use tokens.

         token = new Token(EOF_INFO, ex.message);
-        message = 'unexpected character';
       } else {
-        token = new Token(EOF_INFO, 0);
-        message = ex.message;
+        token = ex.position;
       }
-      compiler.cancel(message, token: token);
+      compiler.cancel(ex.message, token: token);
     }
     ElementListener listener = new ElementListener(compiler, compilationUnit);
     PartialParser parser = new PartialParser(listener);