Bug 1641255 - Remove bad WindowListener reference from android reftest harness; r=jya

WindowListener was removed in bug 1632098, but this reference was left behind.

Differential Revision: https://phabricator.services.mozilla.com/D77098

layout/tools/reftest/api.js

@@ -148,7 +148,6 @@ this.reftest = class extends ExtensionAPI {
     this.chromeHandle = null;
 
     if (Services.appinfo.OS == "Android") {
-      Services.wm.removeListener(WindowListener);
       OnRefTestUnload();
       Cu.unload("resource://reftest/reftest.jsm");
     }