Bug 1543983 - Whitelist about:compat as a secure page on Fennec; r=snorp

Whitelist about:compat as a secure page on Fennec

Differential Revision: https://phabricator.services.mozilla.com/D27391

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

mobile/android/chrome/content/browser.js

@@ -5663,7 +5663,7 @@ var IdentityHandler = {
       return this.IDENTITY_MODE_IDENTIFIED;
     }
 
-    let whitelist = /^about:(about|accounts|addons|buildconfig|cache|config|crashes|devices|downloads|experiments|fennec|firefox|feedback|home|license|logins|logo|memory|mozilla|networking|privatebrowsing|rights|serviceworkers|support|telemetry|webrtc)($|\?)/i;
+    let whitelist = /^about:(about|accounts|addons|buildconfig|cache|compat|config|crashes|devices|downloads|experiments|fennec|firefox|feedback|home|license|logins|logo|memory|mozilla|networking|privatebrowsing|rights|serviceworkers|support|telemetry|webrtc)($|\?)/i;
     if (uri.schemeIs("about") && whitelist.test(uri.spec)) {
         return this.IDENTITY_MODE_CHROMEUI;
     }