Node tests causing SEGV

[dcousens]

@calvinmetcalf can you verify?

[fanatid]

$ git clone git@github.com:crypto-browserify/pbkdf2.git
...
$ cd pbkdf2
$ npm i
...
$ npm run test
...
    node pbkdf2 pbkdf2-compat pbkdf2 sha1 should throw Bad key length: Segmentation fault (core dumped)
$ node -v
v5.6.0
$ npm -v
3.6.0

[calvinmetcalf]

confirmed, this is actually a node bug... it would seem

[calvinmetcalf]

filing an issue

[fanatid]

This issue is not actual now
nodejs/node#5397 merged
NaN check added in #27