add parameter type declarations to private methods

Author: xabbuh

Tests/Parser/ReaderTest.php

@@ -93,7 +93,7 @@ public function testToEnd()
         $this->assertTrue($reader->isEOF());
     }
 
-    private function assignPosition(Reader $reader, $value)
+    private function assignPosition(Reader $reader, int $value)
     {
         $position = new \ReflectionProperty($reader, 'position');
         $position->setAccessible(true);