api(console.count): remove the "same line" requirement

None of Firefox, Chrome or Safari currently keeps a per line counter. Only the passed in string is used as a counter identifier. 

The currently spec-ed out behavior is not desirable or useful in practice.
api(console.count): add a spec for console.count w/o label
Merge pull request #22 from IgorMinar/patch-3

api(console.count): remove the "same line" requirement