Removed unused ivar (`_launchOptions`) from `RCTRootView`

Reviewed By: javache

Differential Revision: D5477683

fbshipit-source-id: 05191c98573fe74105d6af2a098f2a8c4479e09c

React/Base/RCTRootView.m

@@ -45,7 +45,6 @@ NSString *const RCTContentDidAppearNotification = @"RCTContentDidAppearNotificat
 {
   RCTBridge *_bridge;
   NSString *_moduleName;
-  NSDictionary *_launchOptions;
   RCTRootContentView *_contentView;
   BOOL _passThroughTouches;
   CGSize _intrinsicContentSize;