remove unused field from private class (#60)
diff --git a/lib/src/parser.dart b/lib/src/parser.dart
index 4beb1de..fd24f88 100644
--- a/lib/src/parser.dart
+++ b/lib/src/parser.dart
@@ -712,9 +712,6 @@
/// Expect [TokenType.STREAM_START].
static const STREAM_START = _State('STREAM_START');
- /// Expect the beginning of an implicit document.
- static const IMPLICIT_DOCUMENT_START = _State('IMPLICIT_DOCUMENT_START');
-
/// Expect [TokenType.DOCUMENT_START].
static const DOCUMENT_START = _State('DOCUMENT_START');