total_watchers_count.js

(function () {
    var i, data, scope,
        count = 0,
        all = document.all,
        len = all.length,
        test = {};

    for (i=0; i < len; i++) {
        data = angular.element(all[i]).data();
        if (data.hasOwnProperty('$scope') && data.$scope.$$watchers) {
            scope = data.$scope;
            if (!test[scope.$id]) {
                test[scope.$id] = true;
                count += scope.$$watchers.length;
            }
        }
    }
    console.log('total = ', count);
})();