Refactored code to allow associating workers with multiple renderers.

chrome/test/data/workers/worker_common.js

 if (!self.postMessage) {
   // This is a shared worker - mimic dedicated worker APIs
   onconnect = function(event) {
     event.ports[0].onmessage = function(e) {
       self.onmessage(e);
     };
     self.postMessage = function(msg, ports) {
       event.ports[0].postMessage(msg, ports);
     };
   };
 }
 onmessage = function(evt) {
   if (evt.data == "ping")
     postMessage("pong");
+  else if (evt.data == "auth")
+    importScripts("/auth-basic");
   else if (/eval.+/.test(evt.data)) {
     try {
       postMessage(eval(evt.data.substr(5)));
     } catch (ex) {
       postMessage(ex);
     }
   }
 }