Fix lifetime issue.

src/parser/plain_text.rs

@@ -37,9 +37,9 @@ fn plain_text_end<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'s s
     recognize(parser_with_context!(any_object_except_plain_text)(context))(input)
 }
 
-impl<'x> RematchObject for PlainText<'x> {
+impl<'x> RematchObject<'x> for PlainText<'x> {
     fn rematch_object<'r, 's>(
-        &self,
+        &'x self,
         _context: Context<'r, 's>,
         input: &'s str,
     ) -> Res<&'s str, Object<'s>> {