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

third_party/WebKit/LayoutTests/inspector-protocol/dom/push-children-on-pseudo-addition.js

+(async function(testRunner) {
+  var {page, session, dp} = await testRunner.startHTML(`
+    <style id='style'>
+    </style>
+    <div id='for-pseudo'><span id='inner-span'></span></div>
+  `, '');
+
+  var DOMHelper = await testRunner.loadScript('../resources/dom-helper.js');
+  var NodeTracker = await testRunner.loadScript('../resources/node-tracker.js');
+  var nodeTracker = new NodeTracker(dp);
+
+  testRunner.log('\n=== Get the Document ===\n');
+  var response = await dp.DOM.getDocument();
+  var bodyId = response.result.root.children[0].children[1].nodeId;
+
+  testRunner.log('\n=== Get immediate children of the body ===\n');
+  dp.DOM.requestChildNodes({nodeId: bodyId});
+  await dp.DOM.onceSetChildNodes();
+
+  testRunner.log('\n=== Add #for-pseudo:before element ===\n');
+  session.evaluate(() => {
+    document.getElementById('style').textContent = '#for-pseudo:before { content: "BEFORE" }';
+  });
+  await dp.DOM.oncePseudoElementAdded();
+
+  for (var node of nodeTracker.nodes()) {
+    if (DOMHelper.attributes(node).get('id') === 'inner-span') {
+      testRunner.log('PASS: #inner-span has been received');
+      testRunner.completeTest();
+      return;
+    }
+  }
+  testRunner.die('FAIL: #inner-span was not received');
+})