Test that DevTools commands can be handled on worker thread when it is in a tight loop

LayoutTests/inspector-protocol/debugger/resources/dedicated-worker-loop.js

+var message_id = 1;
+onmessage = function(event) {
+  doWork();
+};
+
+function doWork() {
+  postMessage("Message #" + message_id++);
+
+  var ts = Date.now();
+  while (true) {
+    if (Date.now() - ts > 1000) {
+        ts = Date.now();
+        postMessage("Message #" + message_id++);
+    }
+  }
+}
+