Forbid setting responseType on all sync XHRs.

LayoutTests/fast/events/xhr-onclick-crash.html

Index: LayoutTests/fast/events/xhr-onclick-crash.html
diff --git a/LayoutTests/fast/events/xhr-onclick-crash.html b/LayoutTests/fast/events/xhr-onclick-crash.html
index 23d152ea02a1d7a22797af6c44f55f2c9c020882..8313295ca8bc68e52ac7f24a9ea94d2623eff9b6 100644
--- a/LayoutTests/fast/events/xhr-onclick-crash.html
+++ b/LayoutTests/fast/events/xhr-onclick-crash.html
@@ -3,11 +3,15 @@ This test passes if it doesn't crash.
 if (window.testRunner)
     testRunner.dumpAsText();
 
+window.jsTestIsAsync = true;

[Nate Chapin, 2014/03/20 19:59:56]

I don't think this does what you want it to. This is a no-op if the test doesn't
use js-test.js. You need to call testRunner.waitUntilDone() here and
testRunnery.notifyDone() instead of finishJSTest().

[davidben, 2014/03/20 20:05:00]

Done.

 xhr = new XMLHttpRequest();
-xhr.open('GET', 'resources/onclick.html', false);
+xhr.open('GET', 'resources/onclick.html', true);
 xhr.responseType = 'document';
-xhr.onload = function () { r = this.responseXML; }
+xhr.onload = function () {
+    var r = this.responseXML;
+    var td = r.getElementById('foo');
+    td.children[0].onclick;
+    finishJSTest();
+};
 xhr.send();
-td = r.getElementById('foo');
-td.children[0].onclick;
 </script>