[DevTools] New harness for inspector-protocol layout tests

third_party/WebKit/LayoutTests/inspector-protocol/animation/animation-pause-infinite.js

+(async function(testRunner) {
+  let {page, session, dp} = await testRunner.startHTML(`
+    <div id='node' style='background-color: red; height: 100px'></div>
+  `, 'Tests that the animation is correctly paused.');
+
+  dp.Animation.enable();
+  session.evaluate(`
+    window.animation = node.animate([{ width: '100px' }, { width: '2000px' }], { duration: 10000, iterations: Infinity });
+  `);
+
+  var response = await dp.Animation.onceAnimationStarted();
+  testRunner.log('Animation started');
+  await dp.Animation.setPaused({ animations: [ response.params.animation.id ], paused: true });
+
+  var nodeWidth = await session.evaluate('node.offsetWidth');
+  var rafWidth = await session.evaluateAsync(`
+    (function rafWidth() {
+        var callback;
+        var promise = new Promise((fulfill) => callback = fulfill);
+        if (window.testRunner)
+            testRunner.layoutAndPaintAsyncThen(() => callback(node.offsetWidth));
+        return promise;
+    })()
+  `);
+  testRunner.log(rafWidth === nodeWidth);
+  testRunner.completeTest();
+})