fixup! Bug 3455: Add DomainIsolator, for isolating circuit by domain.

TorStartupService is not launched on Android, so initialize FPI in
another script that is used by GV (and only once, if I understand
correctly).

mobile/android/components/geckoview/GeckoViewStartup.jsm

@@ -17,6 +17,7 @@ ChromeUtils.defineESModuleGetters(lazy, {
   PdfJs: "resource://pdf.js/PdfJs.sys.mjs",
   Preferences: "resource://gre/modules/Preferences.sys.mjs",
   RFPHelper: "resource://gre/modules/RFPHelper.sys.mjs",
+  TorDomainIsolator: "resource://gre/modules/TorDomainIsolator.sys.mjs",
 });
 
 const { XPCOMUtils } = ChromeUtils.importESModule(
@@ -258,6 +259,8 @@ class GeckoViewStartup {
           "GeckoView:SetLocale",
         ]);
 
+        lazy.TorDomainIsolator.init();
+
         Services.obs.addObserver(this, "browser-idle-startup-tasks-finished");
         Services.obs.addObserver(this, "handlersvc-store-initialized");