Worker: Set Worker.onerror handler to fail test early

This adds Worker.onerror handler in net/data/websocket/connect_check.html.

This is useful for debugging https://crbug.com/1000117. Without this
change, SSLUITest.TestWSSInvalidCert waits for timeout long time.

Bug: 1000117
Change-Id: Ibe0e73fcf30423bb0a1c0cf5b38384355605905c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1877496
Auto-Submit: Hiroki Nakagawa <nhiroki@chromium.org>
Commit-Queue: Yutaka Hirano <yhirano@chromium.org>
Reviewed-by: Yutaka Hirano <yhirano@chromium.org>
Cr-Commit-Position: refs/heads/master@{#708954}

net/data/websocket/connect_check.html

@@ -22,6 +22,7 @@ var workerConnection = new Promise((resolve, reject) => {
       reject();
     }
   };
+  worker.onerror = reject;
 
   // Start the worker.
   worker.postMessage('');