Bug 1443904 - Fix enabled/disabled logic for choice prompts in BasicGeckoViewPrompt r=snorp

mobile/android/geckoview_example/src/main/java/org/mozilla/geckoview_example/BasicGeckoViewPrompt.java

@@ -360,7 +360,7 @@ final class BasicGeckoViewPrompt implements GeckoSession.PromptDelegate {
                 final ModifiableChoice item = getItem(position);
                 return !item.choice.separator && !item.choice.disabled &&
                         ((type != Choice.CHOICE_TYPE_SINGLE && type != Choice.CHOICE_TYPE_MULTIPLE) ||
-                         item.choice.items != null);
+                         item.choice.items == null);
             }
 
             @Override