message: update a the ByteInput comment
  At some ByteInput switched to being backed by actual bytes
  rather than a string. This commit just removes the dangling
  reference to the old representation.
diff: @@ -223,10 +223,6 @@ impl<'t> Input for CharInput<'t> {
  }
  /// An input reader over bytes.
  -///
  -/// N.B. We represent the reader with a string for now, since that gives us
  -/// easy access to necessary Unicode decoding (used for word boundary look
  -/// ahead/look behind).
  #[derive(Clone, Copy, Debug)]
  pub struct ByteInput<'t> {
  text: &'t [u8],
  