Bug 1560554 - Disable warning prompt from about:networking r=JuniorHsu

Differential Revision: https://phabricator.services.mozilla.com/D35535

--HG--
extra : moz-landing-system : lando

modules/libpref/init/all.js

@@ -1510,7 +1510,7 @@ pref("network.protocol-handler.external.le", false);   // file
 pref("network.protocol-handler.expose-all", true);
 
 // Warning for about:networking page
-pref("network.warnOnAboutNetworking", true);
+pref("network.warnOnAboutNetworking", false);
 
 // Example: make IMAP an exposed protocol
 // pref("network.protocol-handler.expose.imap", true);