Sync XHR on Worker should not crash when response arrives immediately

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

Index: third_party/WebKit/LayoutTests/http/tests/xmlhttprequest/resources/cross-origin-unsupported-url.js
diff --git a/third_party/WebKit/LayoutTests/http/tests/xmlhttprequest/resources/cross-origin-unsupported-url.js b/third_party/WebKit/LayoutTests/http/tests/xmlhttprequest/resources/cross-origin-unsupported-url.js
index 28b9b8e91b9cf7bd6352e057ee94304a3c8a0445..ac1e26f14bbceda0a801ccc18a0b11d50cac2d31 100644
--- a/third_party/WebKit/LayoutTests/http/tests/xmlhttprequest/resources/cross-origin-unsupported-url.js
+++ b/third_party/WebKit/LayoutTests/http/tests/xmlhttprequest/resources/cross-origin-unsupported-url.js
@@ -10,7 +10,22 @@ 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");