Add YogaNode.cloneWithoutChildren

Summary: Adding flat clone method back to YogaNode for reconciliation.

Reviewed By: davidaurelio

Differential Revision: D14683019

fbshipit-source-id: 08ed2ffbb16052cb11aa464f67a7ba9a64297985

java/com/facebook/yoga/YogaNode.java

@@ -221,4 +221,6 @@ public abstract class YogaNode {
   public abstract void print();
 
   public abstract void setStyleInputs(float[] styleInputs, int size);
+
+  public abstract YogaNode cloneWithoutChildren();
 }