for ios

git-svn-id: svn://192.168.3.15/activex/AVS/Sources/TeamlabOffice/trunk/OfficeWeb@68047 954022d7-b5bf-4e40-9824-e11837661b57

Common/browser.js

@@ -68,7 +68,7 @@ AscBrowser.zoom = 1;
 
 AscBrowser.checkZoom = function()
 {
-    if (AscBrowser.isChrome)
+    if (AscBrowser.isChrome && document && document.firstElementChild)
     {
         document.firstElementChild.style.zoom = "reset";
         AscBrowser.zoom = window.outerWidth / window.innerWidth;