Fix two testharness.js tests with harness errors due to stray asserts

All asserts need to be in a step func. Unfortunately this makes the
tests more verbose.

Found in https://github.com/web-platform-tests/wpt/pull/8748#issuecomment-398954260.

Change-Id: Ib15270d6093ea094b0f8c387cc4370f5154cf5dd
Reviewed-on: https://chromium-review.googlesource.com/1109689
Commit-Queue: Robert Ma <robertma@chromium.org>
Reviewed-by: Robert Ma <robertma@chromium.org>
Cr-Commit-Position: refs/heads/master@{#569401}

third_party/WebKit/LayoutTests/fast/dom/custom/svg-use-shadow-tree-expected.txt

-CONSOLE ERROR: line 2748: Uncaught Error: assert_false: Should not call createdCallback in UA ShadowRoot. expected false got true
-CONSOLE ERROR: line 2748: Uncaught Error: assert_false: Should not call attachedCallback in UA ShadowRoot. expected false got true
-CONSOLE ERROR: line 2748: Uncaught Error: assert_false: Should not call createdCallback in UA ShadowRoot. expected false got true
-CONSOLE ERROR: line 2748: Uncaught Error: assert_false: Should not call attachedCallback in UA ShadowRoot. expected false got true
 This is a testharness.js-based test.
-Harness Error. harness_status.status = 1 , harness_status.message = Uncaught Error: assert_false: Should not call attachedCallback in UA ShadowRoot. expected false got true
-PASS SVG <use> shadow trees should not be exposed through custom elements.
+FAIL SVG <use> shadow trees should not be exposed through custom elements. assert_false: Should not call createdCallback in UA ShadowRoot. expected false got true
 Harness: the test ran to completion.
 

third_party/WebKit/LayoutTests/fast/dom/custom/svg-use-shadow-tree.html

@@ -23,6 +23,8 @@
 <script>
 "use strict";
 
+var t = async_test("SVG <use> shadow trees should not be exposed through custom elements.");
+
 var instances = [];
 
 function createPrototype(superClass) {
@@ -34,40 +36,48 @@ function createPrototype(superClass) {
             return scope;
         }
         createdCallback() {
+            t.step(() => {
                 this.instanceId = instances.length;
                 instances[this.instanceId] = this;
                 assert_false(this.ownerScope instanceof ShadowRoot,
                     "Should not call createdCallback in UA ShadowRoot.");
+            });
         }
         attachedCallback() {
+            t.step(() => {
                 assert_false(this.ownerScope instanceof ShadowRoot,
                     "Should not call attachedCallback in UA ShadowRoot.");
                 assert_equals(instances[this.instanceId], this);
+            });
         }
         detachedCallback() {
+            t.step(() => {
                 assert_false(this.ownerScope instanceof ShadowRoot,
                     "Should not call detachedCallback in UA ShadowRoot.");
                 assert_equals(instances[this.instanceId], this);
+            });
         }
         attributeChangedCallback() {
+            t.step(() => {
                 assert_unreached("attributeChangedCallback should never be called.");
+            });
         }
     };
     return ElementType.prototype;
 }
 
-// <rect is=x-rect>
-var XRectElement = document.registerElement('x-rect', {
+t.step(function () {
+    // <rect is=x-rect>
+    var XRectElement = document.registerElement('x-rect', {
         extends: 'rect',
         prototype: createPrototype(SVGRectElement),
-});
+    });
 
-// <x-test>
-var XTestElement = document.registerElement('x-test', {
+    // <x-test>
+    var XTestElement = document.registerElement('x-test', {
         prototype: createPrototype(HTMLElement),
-});
+    });
 
-test(function () {
     var template = document.getElementById("template");
     var svg = document.importNode(template.content, true).firstElementChild;
     var usedGroup = svg.getElementById("used-group");
@@ -97,5 +107,9 @@ test(function () {
         assert_true(instances[i].ownerScope instanceof Document,
             "No instances should be inside a ShadowRoot.");
     }
-}, "SVG <use> shadow trees should not be exposed through custom elements.");
+
+    // Any callbacks will have been scheduled and run in microtasks,
+    // so end test after that.
+    t.step_timeout(t.step_func_done());
+});
 </script>

third_party/WebKit/LayoutTests/http/tests/webaudio/autoplay-crossorigin-expected.txt

-CONSOLE WARNING: line 13: The AudioContext was not allowed to start. It must be resumed (or created) from a user gesture event handler.
-CONSOLE WARNING: line 23: The AudioContext was not allowed to start. It must be resumed (or created) from a user gesture event handler.
-CONSOLE WARNING: line 36: The AudioContext was not allowed to start. It must be resumed (or created) from a user gesture event handler.
-CONSOLE ERROR: line 2684: Uncaught Error: assert_equals: stateAfterClick expected "running" but got "suspended"
+CONSOLE WARNING: line 13: The AudioContext was not allowed to start. It must be resumed (or created) from a user gesture event handler. https://goo.gl/7K7WLu
+CONSOLE WARNING: line 13: The Web Audio autoplay policy will be re-enabled in Chrome 70 (October 2018). Please check that your website is compatible with it. https://goo.gl/7K7WLu
+CONSOLE WARNING: line 23: The AudioContext was not allowed to start. It must be resumed (or created) from a user gesture event handler. https://goo.gl/7K7WLu
+CONSOLE WARNING: line 32: The AudioContext was not allowed to start. It must be resumed (or created) from a user gesture event handler. https://goo.gl/7K7WLu
+CONSOLE WARNING: line 36: The AudioContext was not allowed to start. It must be resumed (or created) from a user gesture event handler. https://goo.gl/7K7WLu
+CONSOLE WARNING: line 36: The Web Audio autoplay policy will be re-enabled in Chrome 70 (October 2018). Please check that your website is compatible with it. https://goo.gl/7K7WLu
 This is a testharness.js-based test.
-Harness Error. harness_status.status = 1 , harness_status.message = Uncaught Error: assert_equals: stateAfterClick expected "running" but got "suspended"
-PASS Verify that autoplaying Web Audio from a cross origin iframe is blocked by mediaPlaybackRequiresUserGesture
+FAIL Verify that autoplaying Web Audio from a cross origin iframe is blocked by mediaPlaybackRequiresUserGesture assert_equals: stateAfterClick expected "running" but got "suspended"
 Harness: the test ran to completion.
 

third_party/WebKit/LayoutTests/http/tests/webaudio/autoplay-crossorigin.html

@@ -5,7 +5,7 @@
 <body></body>
 <script>
 async_test(t => {
-  window.addEventListener('message', e => {
+  window.addEventListener('message', t.step_func(e => {
     switch (e.data.msg) {
       case 'clickme':
         if (!('eventSender' in window))
@@ -37,7 +37,7 @@ async_test(t => {
       default:
         assert_unreached();
     }
-  });
+  }));
 
   var f = document.createElement('iframe');
   f.src = 'http://localhost:8000/webaudio/resources/autoplay-crossorigin-iframe.html';