Revert "CLEANUP: This file no longer seems to be used"

This reverts commit 5c2893c8f9.

app/assets/javascripts/discourse/lib/transition_helper.js

@@ -0,0 +1,43 @@
+/**
+  CSS transitions are a PITA, often we need to queue some js after a transition, this helper ensures
+  it happens after the transition.
+
+  SO: http://stackoverflow.com/questions/9943435/css3-animation-end-techniques
+
+
+  @class TransitionHelper
+  @namespace Discourse
+  @module Discourse
+**/
+
+var dummy, eventNameHash, transitionEnd, _getTransitionEndEventName;
+
+dummy = document.createElement("div");
+
+eventNameHash = {
+  webkit: "webkitTransitionEnd",
+  Moz: "transitionend",
+  O: "oTransitionEnd",
+  ms: "MSTransitionEnd"
+};
+
+_getTransitionEndEventName = function() {
+  var retValue;
+  retValue = "transitionend";
+  Object.keys(eventNameHash).some(function(vendor) {
+    if (vendor + "TransitionProperty" in dummy.style) {
+      retValue = eventNameHash[vendor];
+      return true;
+    }
+  });
+  return retValue;
+};
+transitionEnd = _getTransitionEndEventName();
+
+Discourse.TransitionHelper = {
+  after: function(element, callback) {
+    return $(element).on(transitionEnd, callback);
+  }
+};
+
+