better form submission in fill() by using events

@@ -740,6 +740,12 @@ Casper.prototype.fill = function fill(selector, vals, submit) {
             var method = (form.getAttribute('method') || "GET").toUpperCase();
             var action = form.getAttribute('action') || "unknown";
             __utils__.log('submitting form to ' + action + ', HTTP ' + method, 'info');
+            var event = document.createEvent('Event');
+            event.initEvent('submit', true, true);
+            if (!form.dispatchEvent(event)) {
+                __utils__.log('unable to submit form', 'warning');
+                return;
+            }
             if (typeof form.submit === "function") {
                 form.submit();
             } else {