IntersectionObserver: use an idle callback to send notifications.

third_party/WebKit/LayoutTests/intersection-observer/containing-block.html

Index: third_party/WebKit/LayoutTests/intersection-observer/containing-block.html
diff --git a/third_party/WebKit/LayoutTests/intersection-observer/containing-block.html b/third_party/WebKit/LayoutTests/intersection-observer/containing-block.html
index f7db8fb8ee8d9878185571d268a8c5056a4582ad..819ec5fabb56d591c05bc4c601b16078449fc36a 100644
--- a/third_party/WebKit/LayoutTests/intersection-observer/containing-block.html
+++ b/third_party/WebKit/LayoutTests/intersection-observer/containing-block.html
@@ -19,81 +19,79 @@
 </div>
 
 <script>
-  description("Test that no notifications are generated when root is not in the containing block chain of target.");
-  var root = document.getElementById("root");
-  var target = document.getElementById("target");
-  var entries = [];
+description("Test that no notifications are generated when root is not in the containing block chain of target.");
+var root = document.getElementById("root");
+var target = document.getElementById("target");
+var entries = [];
 
-  function observer_callback(changes) {
-    changes.forEach(function(e) { entries.push(e) });
-  }
-  new IntersectionObserver(observer_callback, {root: root}).observe(target);
+var observer = new IntersectionObserver(
+    changes => { entries = entries.concat(changes) },
+    { root: root }
+);
 
-  function step0() {
-    setTimeout(function() {
-      shouldBeEqualToNumber("entries.length", 0);
-      target.style.top = "10px";
-      requestAnimationFrame(step1);
-    });
-  }
+onload = function() {
+  observer.observe(target);
+  shouldBeEqualToNumber("entries.length", 0);
+  target.style.top = "10px";
+  // See README for explanation of double RAF.
+  requestAnimationFrame(() => { requestAnimationFrame(step1) });
+};
 
-  function step1() {
-    setTimeout(function() {
-      shouldBeEqualToNumber("entries.length", 1);
-      shouldBeEqualToNumber("entries[0].boundingClientRect.left", 58);
-      shouldBeEqualToNumber("entries[0].boundingClientRect.right", 158);
-      shouldBeEqualToNumber("entries[0].boundingClientRect.top", 18);
-      shouldBeEqualToNumber("entries[0].boundingClientRect.bottom", 118);
-      shouldBeEqualToNumber("entries[0].intersectionRect.left", 58);
-      shouldBeEqualToNumber("entries[0].intersectionRect.right", 158);
-      shouldBeEqualToNumber("entries[0].intersectionRect.top", 18);
-      shouldBeEqualToNumber("entries[0].intersectionRect.bottom", 118);
-      shouldBeEqualToNumber("entries[0].rootBounds.left", 8);
-      shouldBeEqualToNumber("entries[0].rootBounds.right", 193);
-      shouldBeEqualToNumber("entries[0].rootBounds.top", 8);
-      shouldBeEqualToNumber("entries[0].rootBounds.bottom", 208);
-      shouldEvaluateToSameObject("entries[0].target", target);
-      target.style.top = "250px";
-      requestAnimationFrame(step2);
-    });
-  }
-
-  function step2() {
-    setTimeout(function() {
-      shouldBeEqualToNumber("entries.length", 2);
-      shouldBeEqualToNumber("entries[1].boundingClientRect.left", 58);
-      shouldBeEqualToNumber("entries[1].boundingClientRect.right", 158);
-      shouldBeEqualToNumber("entries[1].boundingClientRect.top", 258);
-      shouldBeEqualToNumber("entries[1].boundingClientRect.bottom", 358);
-      shouldBeEqualToNumber("entries[1].intersectionRect.left", 0);
-      shouldBeEqualToNumber("entries[1].intersectionRect.right", 0);
-      shouldBeEqualToNumber("entries[1].intersectionRect.top", 0);
-      shouldBeEqualToNumber("entries[1].intersectionRect.bottom", 0);
-      shouldBeEqualToNumber("entries[1].rootBounds.left", 8);
-      shouldBeEqualToNumber("entries[1].rootBounds.right", 193);
-      shouldBeEqualToNumber("entries[1].rootBounds.top", 8);
-      shouldBeEqualToNumber("entries[1].rootBounds.bottom", 208);
-      shouldEvaluateToSameObject("entries[1].target", target);
-      root.style.position = "static";
-      target.style.top = "10px";
-      requestAnimationFrame(step3);
-    });
+function step1() {
+  entries = entries.concat(observer.takeRecords());
+  shouldBeEqualToNumber("entries.length", 1);
+  if (entries.length > 0) {
+    shouldBeEqualToNumber("entries[0].boundingClientRect.left", 58);
+    shouldBeEqualToNumber("entries[0].boundingClientRect.right", 158);
+    shouldBeEqualToNumber("entries[0].boundingClientRect.top", 18);
+    shouldBeEqualToNumber("entries[0].boundingClientRect.bottom", 118);
+    shouldBeEqualToNumber("entries[0].intersectionRect.left", 58);
+    shouldBeEqualToNumber("entries[0].intersectionRect.right", 158);
+    shouldBeEqualToNumber("entries[0].intersectionRect.top", 18);
+    shouldBeEqualToNumber("entries[0].intersectionRect.bottom", 118);
+    shouldBeEqualToNumber("entries[0].rootBounds.left", 8);
+    shouldBeEqualToNumber("entries[0].rootBounds.right", 193);
+    shouldBeEqualToNumber("entries[0].rootBounds.top", 8);
+    shouldBeEqualToNumber("entries[0].rootBounds.bottom", 208);
+    shouldEvaluateToSameObject("entries[0].target", target);
   }
+  target.style.top = "250px";
+  requestAnimationFrame(step2);
+}
 
-  function step3() {
-    setTimeout(function() {
-      shouldBeEqualToNumber("entries.length", 2);
-      target.style.top = "250px";
-      requestAnimationFrame(step4);
-    });
+function step2() {
+  entries = entries.concat(observer.takeRecords());
+  shouldBeEqualToNumber("entries.length", 2);
+  if (entries.length > 1) {
+    shouldBeEqualToNumber("entries[1].boundingClientRect.left", 58);
+    shouldBeEqualToNumber("entries[1].boundingClientRect.right", 158);
+    shouldBeEqualToNumber("entries[1].boundingClientRect.top", 258);
+    shouldBeEqualToNumber("entries[1].boundingClientRect.bottom", 358);
+    shouldBeEqualToNumber("entries[1].intersectionRect.left", 0);
+    shouldBeEqualToNumber("entries[1].intersectionRect.right", 0);
+    shouldBeEqualToNumber("entries[1].intersectionRect.top", 0);
+    shouldBeEqualToNumber("entries[1].intersectionRect.bottom", 0);
+    shouldBeEqualToNumber("entries[1].rootBounds.left", 8);
+    shouldBeEqualToNumber("entries[1].rootBounds.right", 193);
+    shouldBeEqualToNumber("entries[1].rootBounds.top", 8);
+    shouldBeEqualToNumber("entries[1].rootBounds.bottom", 208);
+    shouldEvaluateToSameObject("entries[1].target", target);
   }
+  root.style.position = "static";
+  target.style.top = "10px";
+  requestAnimationFrame(step3);
+}
 
-  function step4() {
-    setTimeout(function() {
-      shouldBeEqualToNumber("entries.length", 2);
-      finishJSTest();
-    });
-  }
+function step3() {
+  entries = entries.concat(observer.takeRecords());
+  shouldBeEqualToNumber("entries.length", 2);
+  target.style.top = "250px";
+  requestAnimationFrame(step4);
+}
 
-  step0();
+function step4() {
+  entries = entries.concat(observer.takeRecords());
+  shouldBeEqualToNumber("entries.length", 2);
+  finishJSTest();
+}
 </script>