Fabric: Removed unused leftovers from ViewShadowNode

Summary:
This method does not have implementation and we don't use it.

Changelog: [Internal] Fabric-specific internal change.

Reviewed By: sammy-SC

Differential Revision: D20423392

fbshipit-source-id: cfb5e4a60dbeca26a968c29d20e74dd6af0bf660

ReactCommon/fabric/components/view/ViewShadowNode.h

@@ -32,8 +32,6 @@ class ViewShadowNode final : public ConcreteViewShadowNode<
       ShadowNode const &sourceShadowNode,
       ShadowNodeFragment const &fragment);
 
-  bool isLayoutOnly() const;
-
  private:
   void updateTraits();
 };