Introduce cloning mechanism for React Shadow Node

Reviewed By: achen1

Differential Revision: D7018869

fbshipit-source-id: beca45b1df9602ebbc9172091b24a2bf44e103f4

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

@@ -67,6 +67,11 @@ public interface ReactShadowNode<T extends ReactShadowNode> {
    */
   boolean isYogaLeafNode();
 
+  /**
+   * @return a mutable copy of the {@link ReactShadowNode}
+   */
+  T mutableCopy();
+
   String getViewClass();
 
   boolean hasUpdates();
@@ -127,8 +132,11 @@ public interface ReactShadowNode<T extends ReactShadowNode> {
 
   T getRootNode();
 
+  @Deprecated() //Replaced by setRootTag method.
   void setRootNode(T rootNode);
 
+  void setRootTag(int rootTag);
+
   void setViewClassName(String viewClassName);
 
   @Nullable
@@ -159,6 +167,8 @@ public interface ReactShadowNode<T extends ReactShadowNode> {
 
   T removeNativeChildAt(int i);
 
+  void removeAllChildren();
+
   void removeAllNativeChildren();
 
   int getNativeChildCount();