simple fix for #2364 (zlib inflate/deflate/gunzip/gzip crashes when called on non-string input)

[nlacasse]

The bug symptom is that calling any of the zlib convenience methods with a non-string argument results in a crash.

The zlibBuffer function is calling removeListener without passing in the event listener itself.

This patch saves the event listeners in variables, and passes them to removeListener.

[bnoordhuis]

@isaacs: You know the zlib code best. Can you review this patch when you're back?

[nlacasse]

Any word on if/when this patch will be reviewed? Thanks!

[isaacs]

@nlacasse I don't get what this is doing. Can you include a test that fails without the patch, and passes with it?

Also, please prefer named function declarations like function onError() { rather than function expressions assigned to a variable like var onError = function() {.

[nlacasse]

@isaacs I changed the function declarations as you asked, and I added a test.

The issue is that zlib is not calling "removeListener" correctly. So on an error (like that caused by invalid input), removeListener gets called improperly and throws an error. The expected behavior is for a useful error to be passed to the callback.

[piscisaureus]

@nlacasse Can you sign the CLA? http://nodejs.org/cla.html

[piscisaureus]

I made some minor edits and squashed everything. When the cla is signed we can land https://gist.github.com/1647651

[nlacasse]

@piscisaureus CLA is signed. Thanks!

[isaacs]

Landed on 40c9348. Thanks!

[piscisaureus]

The related commit incorrectly references #2365. Adding backreference.