[DevTools] New harness for inspector-protocol layout tests

third_party/WebKit/LayoutTests/inspector-protocol/animation/animation-multiple-frames.js

+(async function(testRunner) {
+  let {page, session, dp} = await testRunner.startBlank('');
+
+  await session.evaluate(`
+    function appendIframe() {
+      var frame = document.createElement('iframe');
+      frame.src = '${testRunner.url('../resources/test-page-trigger-animation.html')}';
+      document.body.appendChild(frame);
+    }
+  `);
+
+  async function appendFrame() {
+    await session.evaluate(`appendIframe()`);
+    testRunner.log('Frame appended');
+  }
+
+  var numberAnimationsCaptured = 0;
+  var lastStartTime = undefined;
+
+  dp.Animation.onAnimationStarted(data => {
+    var animation = data.params.animation;
+
+    if (!lastStartTime || animation.startTime >= lastStartTime)
+      testRunner.log('Animation started: start time is valid');
+    else if (lastStartTime)
+      testRunner.log('Animation started: invalid startTime!' + animation.startTime + '.' + lastStartTime);
+    lastStartTime = animation.startTime;
+    numberAnimationsCaptured++;
+
+    if (numberAnimationsCaptured < 10)
+      appendFrame();
+    else
+      testRunner.completeTest();
+  });
+
+  dp.Animation.enable();
+  appendFrame();
+})