The Tor Browser / file revision

 const Cu = Components.utils;

 function run_test() {

   var sb1 = Cu.Sandbox("http://www.blah.com");

   var sb2 = Cu.Sandbox("http://www.blah.com");

   var sb3 = Cu.Sandbox(this);

   var sb4 = Cu.Sandbox("http://www.other.com");

   var rv;

   // Components is normally hidden from content on the XBL scope chain, but we

   // expose it to content here to make sure that the security wrappers work

   // regardless.

   [sb1, sb2, sb4].forEach(function(x) { x.Components = Cu.getComponentsForScope(x); });

   // non-chrome accessing chrome Components

   sb1.C = Components;

   checkThrows("C.utils", sb1);

   checkThrows("C.classes", sb1);

   // non-chrome accessing own Components

   do_check_eq(Cu.evalInSandbox("typeof Components.interfaces", sb1), 'object');

   do_check_eq(Cu.evalInSandbox("typeof Components.utils", sb1), 'undefined');

   do_check_eq(Cu.evalInSandbox("typeof Components.classes", sb1), 'undefined');

   // Make sure an unprivileged Components is benign.

   var C2 = Cu.evalInSandbox("Components", sb2);

   var whitelist = ['interfaces', 'interfacesByID', 'results', 'isSuccessCode', 'QueryInterface'];

   for (var prop in Components) {

     do_print("Checking " + prop);

     do_check_eq((prop in C2), whitelist.indexOf(prop) != -1);

   }

   // non-chrome same origin

   sb1.C2 = C2;

   do_check_eq(Cu.evalInSandbox("typeof C2.interfaces", sb1), 'object');

   do_check_eq(Cu.evalInSandbox("typeof C2.utils", sb1), 'undefined');

   do_check_eq(Cu.evalInSandbox("typeof C2.classes", sb1), 'undefined');

   // chrome accessing chrome

   sb3.C = Components;

   rv = Cu.evalInSandbox("C.utils", sb3);

   do_check_eq(rv, Cu);

   // non-chrome cross origin

   sb4.C2 = C2;

   checkThrows("C2.interfaces", sb4);

   checkThrows("C2.utils", sb4);

   checkThrows("C2.classes", sb4);

 }

 function checkThrows(expression, sb) {

   var result = Cu.evalInSandbox('(function() { try { ' + expression + '; return "allowed"; } catch (e) { return e.toString(); }})();', sb);

   do_check_true(!!/denied/.exec(result));

 }