added a null check on accessibilityStates

Summary:
Added a check for null on `accessibilityStates`.
Now, if a null value is passed in to the prop, it simply does not do anything.

Reviewed By: achen1

Differential Revision: D9034714

fbshipit-source-id: caffa41a1d8b08d5358d085e4e268e8e6f1c9344

Author: Ziqi Chen

ReactAndroid/src/main/java/com/facebook/react/uimanager/BaseViewManager.java

@@ -128,6 +128,9 @@ public void setAccessibilityRole(T view, String accessibilityRole) {
   public void setViewStates(T view, ReadableArray accessibilityStates) {
     view.setSelected(false);
     view.setEnabled(true);
+    if (accessibilityStates == null) {
+      return;
+    }
     for (int i = 0; i < accessibilityStates.size(); i++) {
       String state = accessibilityStates.getString(i);
       if (state.equals("selected")) {