Fixed: WindowObserver ignoring primary browser window if instantiated before window visible

lib/windowObserver.js

Index: lib/windowObserver.js
===================================================================
--- a/lib/windowObserver.js
+++ b/lib/windowObserver.js
@@ -35,15 +35,23 @@
   this._listener  = listener;
   this._when = when;
 
+  let windows = [];
   let e = Services.wm.getZOrderDOMWindowEnumerator(null, true);
-  if (!e.hasMoreElements())
+  while (e.hasMoreElements())
+    windows.push(e.getNext());
+
+  // Check if there are any windows that we missed
+  let eAll = Services.ww.getWindowEnumerator();
+  while (eAll.hasMoreElements())
   {
-    // On Linux the list returned will be empty, see bug 156333. Fall back to random order.
-    e = Services.wm.getEnumerator(null);
+    let element = eAll.getNext();
+    if (windows.indexOf(element) < 0)
+      windows.push(element);
   }
-  while (e.hasMoreElements())
+  
+  for (let i = 0; i < windows.length; i++)
   {
-    let window = e.getNext().QueryInterface(Ci.nsIDOMWindow);
+    let window = windows[i].QueryInterface(Ci.nsIDOMWindow);
     if (when == "start" || window.document.readyState == "complete")
       this._listener.applyToWindow(window);
     else