webBrowserFrame sandbox attribute in Access 2013 web app

Hi

It seems Microsoft changed webBrowserFrame sandbox attribute recently.

Now we always get the following message in the Chrome console:
Error while parsing the 'sandbox' attribute: 'true' is an invalid sandbox flag.
Blocked script execution in 'https://***.sharepoint.com/***/***.aspx' because the document's frame is sandboxed and the 'allow-scripts' permission is not set.

Here is the related code in cdn.sharepointonline.com/9750/_layouts/15/inc/accsvc/accessserverscripts.js

$w7_2:function(){
a:;
this.$6F_2=document.createElement("iframe");
this.$6F_2.frameBorder="0";
this.$6F_2.setAttribute("sandbox","true");
this.$6G_2=document.createElement("div");
this.$6G_2.className="acc-error-message";
this.$6G_2.style.display="none";this.$Io_2=document.createElement("div");
this.$Io_2.className="tb-wrapper";
this.$Io_2.appendChild(this.$6F_2);
this.$Io_2.appendChild(this.$6G_2);
this.set_MainDomElement(this.$Io_2);
this.applyDefaultStyle()
}