Fix the testharness async test API usage

third_party/WebKit/LayoutTests/shadow-dom/pointer-lock-in-shadow.html

Index: third_party/WebKit/LayoutTests/shadow-dom/pointer-lock-in-shadow.html
diff --git a/third_party/WebKit/LayoutTests/shadow-dom/pointer-lock-in-shadow.html b/third_party/WebKit/LayoutTests/shadow-dom/pointer-lock-in-shadow.html
index da2b77b181c683fc71308f1e85596b8cab153f8b..d7faf9529111567081c8a7a8bb076878b8b81761 100644
--- a/third_party/WebKit/LayoutTests/shadow-dom/pointer-lock-in-shadow.html
+++ b/third_party/WebKit/LayoutTests/shadow-dom/pointer-lock-in-shadow.html
@@ -30,12 +30,9 @@
 
 <script>
 async_test((test) => {
-    document.onpointerlockerror = () => {
-        assert_true(false, 'onpointerlockerror is not expected.');
-        test.done();
-    };
+    document.onpointerlockerror = test.unreached_func('onpointerlockerror is not expected.');
 
-    document.onpointerlockchange = () => {
+    document.onpointerlockchange = test.step_func(() => {
         // Not interested in handling before or after exitPointerLock.
         if (document.pointerLockElement === null)
             return;
@@ -49,7 +46,7 @@ async_test((test) => {
 
         document.exitPointerLock();
         test.done();
-    };
+    });
 
     convertTemplatesToShadowRootsWithin(host);
     var host3 = host2.shadowRoot.querySelector('#host3');
@@ -57,12 +54,14 @@ async_test((test) => {
     var host5 = host2.shadowRoot.querySelector('#host5');
 
     // All pointerLockElement should default to null.
-    assert_equals(document.pointerLockElement, null);
-    assert_equals(host.shadowRoot.pointerLockElement, null);
-    assert_equals(host2.shadowRoot.pointerLockElement, null);
-    assert_equals(host3.shadowRoot.pointerLockElement, null);
-    assert_equals(host4.shadowRoot.pointerLockElement, null);
-    assert_equals(host5.shadowRoot.pointerLockElement, null);
+    test.step(() => {
+        assert_equals(document.pointerLockElement, null);
+        assert_equals(host.shadowRoot.pointerLockElement, null);
+        assert_equals(host2.shadowRoot.pointerLockElement, null);
+        assert_equals(host3.shadowRoot.pointerLockElement, null);
+        assert_equals(host4.shadowRoot.pointerLockElement, null);
+        assert_equals(host5.shadowRoot.pointerLockElement, null);
+    });
 
     var canvas = host3.shadowRoot.querySelector('canvas');
     canvas.requestPointerLock();