diff -r 000000000000 -r 6474c204b198 dom/workers/test/bug1020226_worker.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/workers/test/bug1020226_worker.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,11 @@
+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);
+});