polyfill: extend support for zlib to node 0.8.x

zlib in 0.8.x is based on streams1, and in 0.10.x it uses streams2. Also
note that the monkeypunching done here operates on the Zlib proto in
both cases (i.e. Deflate's prototype's prototype), so it catches all of
the zlib methods. Clever clever creationix!