Mark model fields final

Summary: These are already considered immutable, but not marked in their class.

Reviewed By: emilsjolander

Differential Revision: D6759564

fbshipit-source-id: 810dc8a9730fb330760d2aedecafcea81cf25cb1

java/com/facebook/yoga/YogaOverflow.java

@@ -17,7 +17,7 @@ public enum YogaOverflow {
   HIDDEN(1),
   SCROLL(2);
 
-  private int mIntValue;
+  private final int mIntValue;
 
   YogaOverflow(int intValue) {
     mIntValue = intValue;