Until now literal and distance code lengths where treated as two
different arrays. But according to rfc they can overlap:

  The code length repeat codes can cross from HLIT + 257 to the
  HDIST + 1 code lengths.  In other words, all code lengths form
  a single sequence of HLIT + HDIST + 258 values.

Now code lengths are decoded in single array which is then split
to literal and distance part.