Removed uses of Function.prototype.bind to maintain support for PhantomJS 1.x

This fixes https://github.com/webpack/style-loader/issues/31

Version 0.8.2 of style-loader introduced a few minor uses of Function.prototype.bind.  Unfortunately, PhantomJS 1.x does not support Function.prototype.bind.  The result is that the current master version of style-loader crashes when used with PhantomJS.

The commit in this PR removes the use of Function.prototype.bind and thus allows style-loader to be used in PhantomJS again.