Add checkpoints to browser history traversal tests

 Initial value of PopStateEvent.state must be null
 Add checkpoints to testing hashchange event
diff --git a/html/browsers/browsing-the-web/history-traversal/PopStateEvent.html b/html/browsers/browsing-the-web/history-traversal/PopStateEvent.html
index 85205c1..8db1d27 100644
--- a/html/browsers/browsing-the-web/history-traversal/PopStateEvent.html
+++ b/html/browsers/browsing-the-web/history-traversal/PopStateEvent.html
@@ -11,6 +11,11 @@
 }, 'initPopStateEvent');
 
 test(function () {
+  var popStateEvent = new PopStateEvent("popstate");
+  assert_equals(popStateEvent.state, null, "the PopStateEvent.state");
+}, "Initial value of PopStateEvent.state must be null");
+
+test(function () {
   var state = history.state;
   var data;
   window.addEventListener('popstate', function (e) {
diff --git a/html/browsers/browsing-the-web/history-traversal/hashchange_event.html b/html/browsers/browsing-the-web/history-traversal/hashchange_event.html
index 4b701ad..287e7a6 100644
--- a/html/browsers/browsing-the-web/history-traversal/hashchange_event.html
+++ b/html/browsers/browsing-the-web/history-traversal/hashchange_event.html
@@ -18,6 +18,12 @@
 
   location.hash = 'foo';
   window.onhashchange = t.step_func(function (e) {
+    assert_true(e.isTrusted);
+    assert_equals(e.target, window);
+    assert_equals(e.type, "hashchange");
+    assert_true(e instanceof HashChangeEvent);
+    assert_true(e.bubbles, "bubble");
+    assert_false(e.cancelable, "cancelable");
     oldURLs.push(e.oldURL);
     newURLs.push(e.newURL);
     if (newURLs.length === 2) {