diff --git a/apps/email/js/cards.js b/apps/email/js/cards.js
index 63096f72a46e..c91ff961f2d6 100644
--- a/apps/email/js/cards.js
+++ b/apps/email/js/cards.js
@@ -6,6 +6,7 @@ var cardsInit = require('cards_init'),
     mozL10n = require('l10n!'),
     evt = require('evt'),
     toaster = require('toaster'),
+    transitionEnd = require('transition_end'),
     hookupInputAreaResetButtons = require('input_areas');
 
 function addClass(domNode, name) {
@@ -121,9 +122,7 @@ var cards = {
 
     // XXX be more platform detecty. or just add more events. unless the
     // prefixes are already gone with webkit and opera?
-    this._cardsNode.addEventListener('transitionend',
-                                     this._onTransitionEnd.bind(this),
-                                     false);
+    transitionEnd(this._cardsNode, this._onTransitionEnd.bind(this), false);
 
     // Listen for visibility changes to let current card know of them too.
     // Do this here instead of each card needing to listen, and needing to know
diff --git a/apps/email/js/cards/folder_picker.js b/apps/email/js/cards/folder_picker.js
index 287dd2cc2de6..de2d6c95e0bc 100644
--- a/apps/email/js/cards/folder_picker.js
+++ b/apps/email/js/cards/folder_picker.js
@@ -7,7 +7,8 @@ var fldFolderItemNode = require('tmpl!./fld/folder_item.html'),
     FOLDER_DEPTH_CLASSES = require('folder_depth_classes'),
     cards = require('cards'),
     model = require('model'),
-    evt = require('evt');
+    evt = require('evt'),
+    transitionEnd = require('transition_end');
 
 require('css!style/folder_cards');
 
@@ -24,7 +25,7 @@ return [
       this.bindContainerHandler(this.accountListContainer, 'click',
                                 this.onClickAccount.bind(this));
 
-      this.addEventListener('transitionend', this.onTransitionEnd.bind(this));
+      transitionEnd(this, this.onTransitionEnd.bind(this));
 
       // If more than one account, need to show the account dropdown
       var accountCount = model.getAccountCount();
diff --git a/apps/email/js/message_list_topbar.js b/apps/email/js/message_list_topbar.js
index 2a99a6b7250c..a5ddccd848ec 100644
--- a/apps/email/js/message_list_topbar.js
+++ b/apps/email/js/message_list_topbar.js
@@ -40,7 +40,8 @@
  *
  */
 define(function(require, exports, module) {
-  var mozL10n = require('l10n!');
+  var mozL10n = require('l10n!'),
+      transitionEnd = require('transition_end');
 
   var proto = {
     domNode: null,
@@ -55,8 +56,7 @@ define(function(require, exports, module) {
 
     createdCallback: function() {
       this.domNode.addEventListener('click', this._onClick.bind(this));
-      this.domNode.addEventListener('transitionend',
-                                    this._onTransitionEnd.bind(this));
+      transitionEnd(this.domNode, this._onTransitionEnd.bind(this));
     },
 
     /**
diff --git a/apps/email/js/toaster.js b/apps/email/js/toaster.js
index bee8a2850c74..faa223ec0604 100644
--- a/apps/email/js/toaster.js
+++ b/apps/email/js/toaster.js
@@ -2,6 +2,7 @@
 define(function(require) {
   var mozL10n = require('l10n!');
   var toasterNode = require('tmpl!./cards/toaster.html');
+  var transitionEnd = require('transition_end');
 
   /**
    * Manages the display of short status notifications, or 'toasts'.
@@ -37,7 +38,7 @@ define(function(require) {
       this.actionButton = this.el.querySelector('.toaster-action');
 
       this.el.addEventListener('click', this.hide.bind(this));
-      this.el.addEventListener('transitionend', this.hide.bind(this));
+      transitionEnd(this.el, this.hide.bind(this));
 
       // The target is used for the action to allow a larger tap target than
       // just the button.
diff --git a/apps/email/js/transition_end.js b/apps/email/js/transition_end.js
new file mode 100644
index 000000000000..eebe077f7600
--- /dev/null
+++ b/apps/email/js/transition_end.js
@@ -0,0 +1,28 @@
+'use strict';
+
+/**
+ * transitionend is not guaranteed to be async after a layout recalulation.
+ * Specifically, a clientHeight read might trigger sync dispatch of
+ * transitionend event to listeners, which could end up calling the function
+ * that did the clientHeight, but the first call would still be stuck waiting
+ * on the clientHeight read to finish. The issue is tracked in bug 1135960. This
+ * is a workaround for that, to guarantee async dispatch by using the async
+ * nature of promise .then callbacks.
+ */
+define(function(require, exports, module) {
+  return function transitionEnd(node, fn, capturing) {
+    function asyncFn(event) {
+      Promise.resolve().then(function() {
+        fn(event);
+      })
+      .catch(function(error) {
+        console.error(error);
+      });
+    }
+    node.addEventListener('transitionend', asyncFn, capturing);
+
+    // Return the function used with addEventListener to allow the caller of
+    // this helper to later call removeEventListener.
+    return asyncFn;
+  };
+});