add Parser.withoutFasta constructor

pkg/analyzer/lib/src/generated/parser.dart

Index: pkg/analyzer/lib/src/generated/parser.dart
diff --git a/pkg/analyzer/lib/src/generated/parser.dart b/pkg/analyzer/lib/src/generated/parser.dart
index 3552b3d80ae5ea782e4a106bf793d501d921e338..765b4c6d7b853e51229af6eaa2082933e44d9050 100644
--- a/pkg/analyzer/lib/src/generated/parser.dart
+++ b/pkg/analyzer/lib/src/generated/parser.dart
@@ -284,11 +284,11 @@ class Parser {
     if (useFasta ?? Parser.useFasta) {
       return new _Parser2(source, errorListener);
     } else {
-      return new Parser._(source, errorListener);
+      return new Parser.withoutFasta(source, errorListener);
     }
   }
 
-  Parser._(this._source, this._errorListener);
+  Parser.withoutFasta(this._source, this._errorListener);
 
   /**
    * Return the current token.