prefixFree = function prefixFree (name) {
  return typeof name === 'string' && name.charAt(0) === '-' ? helpers.stripPrefix(name) : name;
}
Check if the given argument is a prefixed string. If it is we return an unprefixed
version, else return it unmodified

@param {Object|string} name - The value to test
@returns {string} A prefix free version of the string