[DevTools] New harness for inspector-protocol layout tests

third_party/WebKit/LayoutTests/inspector-protocol/animation/animation-css-replay.js

+(async function(testRunner) {
+  let {page, session, dp} = await testRunner.startHTML(`
+    <div id='node' style='background-color: red; height: 100px; transition: width 100ms; width: 100px'></div>
+  `, '');
+
+  dp.Animation.enable();
+  session.evaluate(`node.style.width = '200px';`);
+
+  var response = await dp.Animation.onceAnimationStarted();
+  testRunner.log("Animation started");
+
+  for (var run = 0; run < 5; run++) {
+    await dp.Animation.seekAnimations({ animations: [ response.params.animation.id ], currentTime: 0 });
+    testRunner.log("Animation seeked");
+  }
+  testRunner.completeTest();
+})