Fabric: Debug Pretty-printing is now debug only feature

Summary: That should save us some app size kilobytes.

Reviewed By: mdvacca

Differential Revision: D10081499

fbshipit-source-id: 2b950768c609b412f9be332c22b6b1e96657e5ea

ReactCommon/fabric/debug/DebugStringConvertibleItem.h

@@ -14,6 +14,8 @@
 namespace facebook {
 namespace react {
 
+#if RN_DEBUG_STRING_CONVERTIBLE
+
 // Trivial implementation of `DebugStringConvertible` abstract class
 // with a stored output; useful for assembling `DebugStringConvertible` values
 // in custom implementations of `getDebugChildren` and `getDebugProps`.
@@ -43,5 +45,7 @@ private:
   SharedDebugStringConvertibleList children_;
 };
 
+#endif
+
 } // namespace react
 } // namespace facebook