Function waitForTick

test/angular/1.6/angular.js:6135–6144

(fn)

    var waitQueue = [];

    function waitForTick(fn) {
      waitQueue.push(fn);
      if (waitQueue.length > 1) return;
      $$rAF(function() {
        for (var i = 0; i < waitQueue.length; i++) {
          waitQueue[i]();
        }
        waitQueue = [];
      });
    }

    return function() {
      var passed = false;