Added lightweight generic annotations

Summary: public

Added lightweight genarics annotations to make the code more readable and help the compiler catch bugs.

Fixed some type bugs and improved bridge validation in a few places.

Reviewed By: javache

Differential Revision: D2600189

fb-gh-sync-id: f81e22f2cdc107bf8d0b15deec6d5b83aacc5b56

React/Base/RCTUtils.h

@@ -60,7 +60,11 @@ RCT_EXTERN UIApplication *RCTSharedApplication(void);
 
 // Return a UIAlertView initialized with the given values
 // or nil if running in an app extension
-RCT_EXTERN UIAlertView *RCTAlertView(NSString *title, NSString *message, id delegate, NSString *cancelButtonTitle, NSArray *otherButtonTitles);
+RCT_EXTERN UIAlertView *RCTAlertView(NSString *title,
+                                     NSString *message,
+                                     id delegate,
+                                     NSString *cancelButtonTitle,
+                                     NSArray<NSString *> *otherButtonTitles);
 
 // Return YES if image has an alpha component
 RCT_EXTERN BOOL RCTImageHasAlpha(CGImageRef image);