[WebSocket] Add close-before-open layout test for workers

LayoutTests/http/tests/websocket/workers/resources/close-before-open.js

+var ws = new WebSocket("ws://127.0.0.1:8880/echo");
+var errorCalled = false;
+ws.onopen = function () {
+    postMessage("FAIL: Unexpected open event on ws");
+};
+ws.onmessage = function () {
+    postMessage("FAIL: Unexpected message event on ws");
+};
+ws.onerror = function () {
+    errorCalled = true;
+};
+ws.onclose = function () {
+    if (errorCalled)
+        postMessage("DONE");
+    else
+        postMessage("FAIL: Error event was not dispatched");
+};
+ws.close();