Bug 806690 - Cancel the current browser load to make sure that we don't catch unexpected load events for about:home; shoulder-r=jdm

DONTBUILD since this in NPOTB for global PB builds

browser/components/privatebrowsing/test/browser/perwindow/browser_privatebrowsing_openlocation.js

@@ -56,6 +56,7 @@ function test() {
     let win = OpenBrowserWindow(options);
     win.addEventListener("load", function onLoad() {
       win.removeEventListener("load", onLoad, false);
+      win.gBrowser.stop(); // Cancel the current home page load
       windowsToClose.push(win);
       callback(win);
     }, false);