Import wpt@357b83b809e3cbc7a1805e7c3ca108a7980d782f

third_party/WebKit/LayoutTests/imported/wpt/web-animations/testcommon.js

 /*
 Distributed under both the W3C Test Suite License [1] and the W3C
 3-clause BSD License [2]. To contribute to a W3C Test Suite, see the
 policies and contribution forms [3].
 
 [1] http://www.w3.org/Consortium/Legal/2008/04-testsuite-license
 [2] http://www.w3.org/Consortium/Legal/2008/03-bsd-license
 [3] http://www.w3.org/2004/10/27-testcases
  */
 
@@ skipping 140 matching lines @@
     function handleFrame() {
       if (--frameCount <= 0) {
         resolve();
       } else {
         window.requestAnimationFrame(handleFrame); // wait another frame
       }
     }
     window.requestAnimationFrame(handleFrame);
   });
 }
+
+// Continually calls requestAnimationFrame until |minDelay| has elapsed
+// as recorded using document.timeline.currentTime (i.e. frame time not
+// wall-clock time).
+function waitForAnimationFramesWithDelay(minDelay) {
+  var startTime = document.timeline.currentTime;
+  return new Promise(function(resolve) {
+    (function handleFrame() {
+      if (document.timeline.currentTime - startTime >= minDelay) {
+        resolve();
+      } else {
+        window.requestAnimationFrame(handleFrame);
+      }
+    }());
+  });
+}