[DevTools] New harness for inspector-protocol layout tests

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

+(async function(testRunner) {
+  let {page, session, dp} = await testRunner.startHTML(`
+    <style type='text/css'>
+    #node.anim {
+        animation: anim 300ms ease-in-out paused;
+    }
+
+    @keyframes anim {
+        from {
+            width: 100px;
+        }
+        to {
+            width: 200px;
+        }
+    }
+    </style>
+    <div id='node' style='background-color: red; width: 100px'></div>
+  `, '');
+
+
+  dp.Animation.enable();
+  session.evaluate('node.classList.add("anim");');
+  await dp.Animation.onceAnimationCreated();
+  testRunner.log('Animation created');
+  await dp.Animation.onceAnimationCanceled();
+  testRunner.log('Animation canceled');
+  testRunner.completeTest();
+})