DevTools: migrate inspector-protocol/dom tests to a new test runner

third_party/WebKit/LayoutTests/inspector-protocol/dom/dom-request-document-with-child-nodes.js

+(async function(testRunner) {
+  var {page, session, dp} = await testRunner.startHTML(`
+    <div id='depth-1'>
+        <div id='depth-2'>
+            <div id='depth-3'>
+                <iframe src='../dom/resources/shadow-dom-iframe.html'></iframe>
+            </div>
+        </div>
+        <div id='targetDiv'></div>
+    </div>
+  `, '');
+  var response = await dp.DOM.getDocument({depth: -1});
+  var iframeOwner = response.result.root.children[0].children[1].children[0].children[0].children[0].children[0];
+  if (iframeOwner.contentDocument.children) {
+    testRunner.die('Error IFrame node should not include children: ' + JSON.stringify(iframeOwner, null, '    '));
+    return;
+  }
+
+  var response = await dp.DOM.getDocument({depth: -1, pierce: true});
+  testRunner.logMessage(response);
+  testRunner.completeTest();
+})
+