Remove now-unused declaration from header file (missed in previous patch). b=332285 r=martijn

dom/src/base/nsGlobalWindow.h

@@ -693,7 +693,6 @@ protected:
 
   friend class nsDOMScriptableHelper;
   friend class nsDOMWindowUtils;
-  static nsIScriptSecurityManager *sSecMan;
   static nsIFactory *sComputedDOMStyleFactory;
 };