Gets all css rules for the document
@param {Boolean} refreshCache true to refresh the internal cache
@return {Object} An object (hash) of rules indexed by selector
function(refreshCache) {
            var result = {},
                selector;

            if (rules === null || refreshCache) {
                CSS.refreshCache();
            }
            for (selector in rules) {
                result[selector] = rules[selector].cssRule;
            }
            return result;
        }