Use null for default value of event handler attributes in XMLHttpRequest....

webkit/data/layout_tests/chrome/fast/js/resources/xhr-event-handler-default.js

+description("This test verifies that XMLHttpRequest object has null event handler attributes by default.");
+
+var xhr = new XMLHttpRequest();
+
+shouldBeNull("xhr.onabort");
+shouldBeNull("xhr.onerror");
+shouldBeNull("xhr.onload");
+shouldBeNull("xhr.onloadstart");
+shouldBeNull("xhr.onprogress");
+shouldBeNull("xhr.onreadystatechange");
+
+var xhr_upload = xhr.upload;
+
+shouldBeNull("xhr_upload.onabort");
+shouldBeNull("xhr_upload.onerror");
+shouldBeNull("xhr_upload.onload");
+shouldBeNull("xhr_upload.onloadstart");
+shouldBeNull("xhr_upload.onprogress");
+
+var successfullyParsed = true;