sync api does not work

Whenever i call sync methods which use `zlibBufferSync()`, I get:

```
# zlib (zlibBufferSync) elipses.txt 16384 {"level":6,"windowBits":15,"memLevel":8,"strategy":0} DeflateRaw -> InflateRaw
not ok 82 Error: buffer error:
---
operator: error
expected: undefined
actual: { [Error: buffer error: ] errno: -5, code: 'Z_BUF_ERROR' }
stack:
Error: buffer error:
at Zlib._binding.onerror (/Users/stephg/Development/checkpad/browserify-zlib/src/index.js:364:17)
at Zlib._error (/Users/stephg/Development/checkpad/browserify-zlib/src/binding.js:229:8)
at Zlib._write (/Users/stephg/Development/checkpad/browserify-zlib/src/binding.js:187:10)
at Zlib.writeSync (/Users/stephg/Development/checkpad/browserify-zlib/src/binding.js:136:15)
at InflateRaw.Zlib._processChunk (/Users/stephg/Development/checkpad/browserify-zlib/src/index.js:520:31)
at Object.zlibBufferSync (/Users/stephg/Development/checkpad/browserify-zlib/src/index.js:235:17)
at Test. (/Users/stephg/Development/checkpad/browserify-zlib/test/test-zlib.js:218:37)
at Test.bound [as _cb] (/Users/stephg/Development/checkpad/browserify-zlib/node_modules/tape/lib/test.js:60:32)
at Test.run (/Users/stephg/Development/checkpad/browserify-zlib/node_modules/tape/lib/test.js:74:14)
at Test.bound [as run] (/Users/stephg/Development/checkpad/browserify-zlib/node_modules/tape/lib/test.js:60:32)
...
```

This is the test:
https://github.com/factisresearch/browserify-zlib/commit/734fbaba0538b455719018168fc89dccab96e357