small compatibility fix for prototype.js

[kemaldaggen]

for (var i in array) loop is causing errors when using less.watch(), this converts loop into standart numerical indexed for loop, so that using less.js with pages that also uses prototype.js would not cause any errors of the following kind:

"name[k].charAt is not a function"

[lukeapage]

damn, we switched on jshint and I thought we caught all the in cases.

[lukeapage]

searched manually for " in " it seems this was the only place we missed. does it completely break when used with prototype? guess you'll want a new release soon.. ?

[kemaldaggen]

thanks. No we do not require any release, we are going for the version we fixed. It works initialy, but when you start watch and change less file, than it immediately breaks because of prototype.js pollution of a lot of native javascript objects.