Issue 3814 - Opening sharing pop-up fails starting with Firefox 47

common.js

Index: common.js
===================================================================
--- a/common.js
+++ b/common.js
@@ -68,20 +68,30 @@
     // to have a fake top level frame to avoid problems with scripts that try to
     // communicate with the first-run page
     var isGecko = ("Components" in window);
     if (isGecko)
     {
       try
       {
         var Ci = Components.interfaces;
-        iframe.contentWindow
+        var docShell = iframe.contentWindow
           .QueryInterface(Ci.nsIInterfaceRequestor)
-          .getInterface(Ci.nsIDocShell)
-          .setIsBrowserInsideApp(Ci.nsIScriptSecurityManager.UNKNOWN_APP_ID);
+          .getInterface(Ci.nsIDocShell);
+
+        if (typeof docShell.frameType != "undefined")
+        {
+          // Gecko 47+
+          docShell.frameType = docShell.FRAME_TYPE_BROWSER;
+        }
+        else
+        {
+          // Legacy branch
+          docShell.setIsBrowserInsideApp(Ci.nsIScriptSecurityManager.UNKNOWN_APP_ID);
+        }
       }
       catch(ex)
       {
         console.error(ex);
       }
     }
 
     var popupMessageReceived = false;