Bug 1567341 - Remove unused serviceManager argument. r=mccr8

Differential Revision: https://phabricator.services.mozilla.com/D106203

js/xpconnect/src/XPCShellImpl.cpp

@@ -1201,8 +1201,7 @@ int XRE_XPCShellMain(int argc, char** argv, char** envp,
       argv += 2;
     }
 
-    nsCOMPtr<nsIServiceManager> servMan;
-    rv = NS_InitXPCOM(getter_AddRefs(servMan), appDir, &dirprovider);
+    rv = NS_InitXPCOM(nullptr, appDir, &dirprovider);
     if (NS_FAILED(rv)) {
       printf("NS_InitXPCOM failed!\n");
       return 1;