fix inflate.push()

Recently found an error in the implementation of the Inflate class. 

Here are some examples:

Original:
http://jsfiddle.net/SLYD6/1/
With patch applied:
http://jsfiddle.net/VEmDA/

The example generates a ~16kb random byte array, compresses, and then decompress it using the Inflate class, feeding it byte by byte. The original version shows an error.