Ignoring recently added test in legacy Firefox driver

Author: barancev

java/client/test/org/openqa/selenium/CorrectEventFiringTest.java

@@ -68,6 +68,7 @@ public void testShouldFireFocusEventWhenClicking() {
 
   @Test
   @Ignore(value = MARIONETTE, issue = "https://github.com/mozilla/geckodriver/issues/906")
+  @Ignore(FIREFOX)
   public void testShouldFireFocusEventInNonTopmostWindow() {
     WebDriver driver2 = new WebDriverBuilder().get();
     try {