Sync XHR on Worker should not crash when response arrives immediately

third_party/WebKit/LayoutTests/http/tests/xmlhttprequest/resources/cross-origin-unsupported-url.js

 if (self.importScripts)
     importScripts("/js-test-resources/js-test.js");
 
 self.jsTestIsAsync = true;
 
 description("Test cross-origin XHRs to CORS-unsupported protocol schemes in the URL.");
 
 var xhr;
 var errorEvent;
 function issueRequest(url, contentType)
 {
     xhr = new XMLHttpRequest();
-    xhr.open('POST', url);
+    // async = false
+    xhr.open('POST', url, false);
+    xhr.onerror = () => testFailed("onerror callback should not be called.");
+    // Assumed a Content-Type that turns it into a non-simple CORS request.
+    if (contentType)
+        xhr.setRequestHeader('Content-Type', contentType);
+    try {
+        xhr.send();
+    } catch(e) {
+        errorEvent = e;
+        shouldBeEqualToString("errorEvent.name", "NetworkError");
+    }
+
+    xhr = new XMLHttpRequest();
+    // async = true
+    xhr.open('POST', url, true);
     xhr.onerror = function (a) {
         errorEvent = a;
         shouldBeEqualToString("errorEvent.type", "error");
         setTimeout(runTest, 0);
     };
     // Assumed a Content-Type that turns it into a non-simple CORS request.
     if (contentType)
         xhr.setRequestHeader('Content-Type', contentType);
 
     shouldNotThrow('xhr.send()');
@@ skipping 11 matching lines @@
         finishJSTest();
         return;
     }
     withContentType = !withContentType;
     if (!withContentType)
         issueRequest(tests[0]);
     else
         issueRequest(tests.shift(), 'application/json');
 }
 runTest();