DevTools: create test infrastructure so devtools drives the test

third_party/WebKit/LayoutTests/http/tests/inspector-unit/tabbed-pane.js

 TestRunner.addResult("This tests if the TabbedPane is keyboard navigable.");
 
 class FocusableWidget extends UI.Widget {
   constructor(name) {
     super();
     this.element.tabIndex = -1;
     this.element.textContent = name;
     this.setDefaultFocusedElement(this.element);
   }
 }
 
 var tabbedPane = new UI.TabbedPane();
 tabbedPane.show(UI.inspectorView.element);
-TestRunner.addSniffer(tabbedPane, '_innerUpdateTabElements').then(tabsAdded);
+TestRunner.addSnifferPromise(tabbedPane, '_innerUpdateTabElements').then(tabsAdded);
 for (var i = 0; i < 10; i++)
   tabbedPane.appendTab(i.toString(), 'Tab ' + i, new FocusableWidget('Widget ' + i));
 
 function tabsAdded() {
   tabbedPane._currentTab.tabElement.focus();
   dumpFocus();
   TestRunner.addResult('Moving right and wrapping around');
   for (var i = 0; i < 20; i++)
     right();
   TestRunner.addResult('Moving left and focusing widgets')
@@ skipping 28 matching lines @@
 
 
 function dumpFocus() {
   var element = document.deepActiveElement();
   if (!element) {
     TestRunner.addResult("null");
     return;
   }
   TestRunner.addResult(element.textContent);
 }