Fix checks based on window.ActiveXObject in IE > 10

CHANGELOG

@@ -3,6 +3,7 @@ CHANGELOG Roundcube Webmail
 
 - Fix bug where max_group_members was ignored when adding a new contact (#1490214)
 - Hide MDN and DSN options in compose if disabled by admin (#1490221)
+- Fix checks based on window.ActiveXObject in IE > 10
 
 RELEASE 1.1-rc
 --------------

program/js/app.js

@@ -8066,7 +8066,7 @@ function rcube_webmail()
     if (plugin && plugin.enabledPlugin)
         return 1;
 
-    if (window.ActiveXObject) {
+    if ('ActiveXObject' in window) {
       try {
         if (plugin = new ActiveXObject("AcroPDF.PDF"))
           return 1;
@@ -8099,7 +8099,7 @@ function rcube_webmail()
     if (plugin && plugin.enabledPlugin)
         return 1;
 
-    if (window.ActiveXObject) {
+    if ('ActiveXObject' in window) {
       try {
         if (plugin = new ActiveXObject("ShockwaveFlash.ShockwaveFlash"))
           return 1;

program/js/common.js

@@ -103,7 +103,7 @@ function roundcube_browser()
   this.xmlhttp_test = function()
   {
     var activeX_test = new Function("try{var o=new ActiveXObject('Microsoft.XMLHTTP');return true;}catch(err){return false;}");
-    this.xmlhttp = (window.XMLHttpRequest || (window.ActiveXObject && activeX_test()));
+    this.xmlhttp = window.XMLHttpRequest || (('ActiveXObject' in window) && activeX_test());
     return this.xmlhttp;
   };