The Tor Browser / file revision

 var p = new Promise(function(resolve, reject) {

   // This causes a runnable to be queued.

   reject(new Error());

   postMessage("loaded");

   // This prevents that runnable from running until the window calls terminate(),

   // at which point the worker goes into the Canceling state and then an

   // AddFeature() is attempted, which fails, which used to result in multiple

   // calls to the error reporter, one after the worker's context had been GCed.

   while (true);

 });