Make WebSocket available again in service workers

third_party/WebKit/LayoutTests/http/tests/serviceworker/websocket/resources/simple.js

+let port;
+let received = false;
+
+function reportFailure(details) {
+  port.postMessage('FAIL: ' + details);
+}
+
+onmessage = event => {
+  port = event.source;
+
+  const ws = new WebSocket('ws://localhost:8880/echo');
+  ws.onopen = () => {
+    ws.send('Hello');
+  };
+  ws.onmessage = msg => {
+    if (msg.data !== 'Hello') {
+      reportFailure('Unexpected reply: ' + msg.data);
+      return;
+    }
+
+    received = true;
+    ws.close();
+  };
+  ws.onclose = () => {
+    if (!received) {
+      reportFailure('Closed before receiving reply');
+      return;
+    }
+
+    port.postMessage('PASS');
+  };
+  ws.onerror = () => {
+    reportFailure('Got an error event');
+  };
+};