Guard against dev menu calling twice

Summary: public

The Dev Menu is for some reason eventually calling twice the callbacks, guard
against it while we don't fix it.

Reviewed By: nicklockwood

Differential Revision: D2600470

fb-gh-sync-id: 50c622d2ab64ce50d51572dbfcc076c2765ce582

React/Profiler/RCTProfile.m

@@ -307,6 +307,10 @@ void RCTProfileInit(RCTBridge *bridge)
 
 NSString *RCTProfileEnd(RCTBridge *bridge)
 {
+  if (!RCTProfileIsProfiling()) {
+    return nil;
+  }
+
   [[NSNotificationCenter defaultCenter] postNotificationName:RCTProfileDidEndProfiling
                                                       object:nil];