Move scanner into pkg/front_end/lib/src/scanner.

pkg/analyzer/lib/src/task/options.dart

Index: pkg/analyzer/lib/src/task/options.dart
diff --git a/pkg/analyzer/lib/src/task/options.dart b/pkg/analyzer/lib/src/task/options.dart
index 4047b3b84c244a407b79b3e8e82179c711eed3dd..60a6dbc21b8476070bfc547d2d29e30a47715095 100644
--- a/pkg/analyzer/lib/src/task/options.dart
+++ b/pkg/analyzer/lib/src/task/options.dart
@@ -173,7 +173,7 @@ class ErrorFilterOptionValidator extends OptionsValidator {
     if (_errorCodes == null) {
       _errorCodes = new HashSet<String>();
       // Engine codes.
-      _errorCodes.addAll(ErrorCode.values.map((ErrorCode code) => code.name));
+      _errorCodes.addAll(errorCodeValues.map((ErrorCode code) => code.name));
     }
     return _errorCodes;
   }