Remove unused @class delcaration

Classes/Network/PonyDebugger/FLEXNetworkObserver.h

@@ -14,8 +14,6 @@
 
 extern NSString *const kFLEXNetworkObserverEnabledStateChangedNotification;
 
-@class FLEXNetworkRecorder;
-
 /// This class swizzles NSURLConnection and NSURLSession delegate methods to observe events in the URL loading system.
 /// High level network events are sent to the default FLEXNetworkRecorder instance which maintains the request history and caches response bodies.
 @interface FLEXNetworkObserver : NSObject