Restructure parser error handling and recovery.

pkg/fasta/lib/src/source/scope_listener.dart

Index: pkg/fasta/lib/src/source/scope_listener.dart
diff --git a/pkg/fasta/lib/src/source/scope_listener.dart b/pkg/fasta/lib/src/source/scope_listener.dart
index 5f0a4facd9fe6c44919fa7dc66161b01a2277090..ecdaf92eb0ff64081c49729336eec00e867c4315 100644
--- a/pkg/fasta/lib/src/source/scope_listener.dart
+++ b/pkg/fasta/lib/src/source/scope_listener.dart
@@ -7,9 +7,6 @@ library fasta.scope_listener;
 import 'package:dart_scanner/src/token.dart' show
     Token;
 
-import 'package:dart_parser/src/error_kind.dart' show
-    ErrorKind;
-
 import 'unhandled_listener.dart' show
     NullValue,
     UnhandledListener;
@@ -206,10 +203,4 @@ abstract class ScopeListener<J> extends UnhandledListener {
     exitLocalScope();
     push(body);
   }
-
-  @override
-  void reportErrorHelper(Token token, ErrorKind kind, Map arguments) {
-    super.reportErrorHelper(token, kind, arguments);
-    debugEvent("error: ${recoverableErrors.last}");
-  }
 }