diff -r 000000000000 -r 6474c204b198 content/base/test/file_bug503481.sjs
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/content/base/test/file_bug503481.sjs	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,43 @@
+// 'timer' is global to avoid getting GCed which would cancel the timer
+var timer;
+const nsITimer = Components.interfaces.nsITimer;
+
+function attemptUnblock(s) {
+  try {
+    let blockedResponse = null;
+    getObjectState("bug503481_" + s, function(x) {blockedResponse = x.wrappedJSObject.r});
+    blockedResponse.finish();
+    setObjectState("bug503481_" + s, null);
+  } catch(e) {
+    dump("unable to unblock " + s + "retrying in half a second\n");
+    timer = Components.classes["@mozilla.org/timer;1"]
+                      .createInstance(nsITimer);
+    timer.initWithCallback(function () { attemptUnblock(s) }, 500, nsITimer.TYPE_ONE_SHOT);
+  }
+}
+
+function handleRequest(request, response)
+{
+  var query = {};
+  request.queryString.split('&').forEach(function (val) {
+    var [name, value] = val.split('=');
+    query[name] = unescape(value);
+  });
+
+  dump("processing:" + request.queryString + "\n");
+
+  if (query.unblock) {
+    attemptUnblock(query.unblock);
+  }
+
+  if (query.blockOn) {
+    response.processAsync();
+    x = { r: response, QueryInterface: function(iid) { return this } };
+    x.wrappedJSObject = x;
+    setObjectState("bug503481_" + query.blockOn, x);
+  }
+
+  response.setHeader("Cache-Control", "no-cache", false);
+  response.setHeader("Content-Type", "text/plain", false);
+  response.write(query.body);
+}