PSA: you can use mocha with istanbul directly

[rstacruz]

Istanbul supports mocha directly. Just run:

istanbul cover _mocha

or with arguments:

istanbul cover _mocha -- -R spec

See https://github.com/gotwarlost/istanbul/issues/44#issuecomment-16093330 for info.

mocha-istanbul exists so that you can use mocha's HTML coverage reporters with istanbul.