Fix back button hiding on popup

ui/app/conf-tx.js

@@ -5,6 +5,7 @@ const h = require('react-hyperscript')
 const connect = require('react-redux').connect
 const actions = require('./actions')
 const txHelper = require('../lib/tx-helper')
+const isPopupOrNotification = require('../../app/scripts/lib/is-popup-or-notification')
 
 const PendingTx = require('./components/pending-tx')
 const PendingMsg = require('./components/pending-msg')
@@ -36,7 +37,7 @@ ConfirmTxScreen.prototype.render = function () {
   var unconfTxList = txHelper(unconfTxs, unconfMsgs)
   var index = state.index !== undefined ? state.index : 0
   var txData = unconfTxList[index] || {}
-  var isNotification = window.METAMASK_UI_TYPE === 'notification'
+  var isNotification = isPopupOrNotification() === 'notification'
 
   return (