Bug 1494276 - Removed unused hasFocus parameter from WindowHelper.onActivate;r=dao

hasFocus parameter was unused in BrowserWindowTracker.jsm

Differential Revision: https://phabricator.services.mozilla.com/D7237

--HG--
extra : moz-landing-system : lando

browser/modules/BrowserWindowTracker.jsm

@@ -127,7 +127,7 @@ var WindowHelper = {
     messageManager.removeMessageListener("Browser:Init", _handleMessage);
   },
 
-  onActivate(window, hasFocus) {
+  onActivate(window) {
     // If this window was the last focused window, we don't need to do anything
     if (window == _trackedWindows[0])
       return;