IntersectionObserver: use an idle callback to send notifications.

third_party/WebKit/LayoutTests/intersection-observer/same-document-zero-size-target.html

Index: third_party/WebKit/LayoutTests/intersection-observer/same-document-zero-size-target.html
diff --git a/third_party/WebKit/LayoutTests/intersection-observer/same-document-zero-size-target.html b/third_party/WebKit/LayoutTests/intersection-observer/same-document-zero-size-target.html
index 215f0058e5c7395ec8bdccdb6e3c53518ce7df8e..51010bb73b0bd48e6234e61893464b5f84cdc767 100644
--- a/third_party/WebKit/LayoutTests/intersection-observer/same-document-zero-size-target.html
+++ b/third_party/WebKit/LayoutTests/intersection-observer/same-document-zero-size-target.html
@@ -6,68 +6,66 @@
 <div style="width:100%; height:700px;"></div>
 
 <script>
-  description("Iintersection observer test with zero-size target element.");
-  var target = document.getElementById("target");
-  var entries = [];
-  observer_callback = function(changes) {
-    for (var i in changes)
-      entries.push(changes[i]);
-  };
-  var observer = new IntersectionObserver(observer_callback, {});
-  observer.observe(target);
-
-  onload = function() {
-    shouldBeEqualToNumber("entries.length", 0);
-    document.scrollingElement.scrollTop = 300;
-    requestAnimationFrame(step1);
-  };
+description("Intersection observer test with zero-size target element.");
+var target = document.getElementById("target");
+var entries = [];
+var observer = new IntersectionObserver(changes => { entries = entries.concat(changes) }, {});
 
-  function step1() {
-    setTimeout(function() {
-      shouldBeEqualToNumber("entries.length", 1);
-      shouldBeEqualToNumber("entries[0].boundingClientRect.left", 8);
-      shouldBeEqualToNumber("entries[0].boundingClientRect.right", 8);
-      shouldBeEqualToNumber("entries[0].boundingClientRect.top", 408);
-      shouldBeEqualToNumber("entries[0].boundingClientRect.bottom", 408);
-      shouldBeEqualToNumber("entries[0].intersectionRect.left", 8);
-      shouldBeEqualToNumber("entries[0].intersectionRect.right", 8);
-      shouldBeEqualToNumber("entries[0].intersectionRect.top", 408);
-      shouldBeEqualToNumber("entries[0].intersectionRect.bottom", 408);
-      shouldBeEqualToNumber("entries[0].rootBounds.left", 0);
-      shouldBeEqualToNumber("entries[0].rootBounds.right", 785);
-      shouldBeEqualToNumber("entries[0].rootBounds.top", 0);
-      shouldBeEqualToNumber("entries[0].rootBounds.bottom", 600);
-      shouldEvaluateToSameObject("entries[0].target", target);
+onload = function() {
+  observer.observe(target);
+  entries.push(...observer.takeRecords());
+  shouldBeEqualToNumber("entries.length", 0);
+  document.scrollingElement.scrollTop = 300;
+  // See README for explanation of double RAF.
+  requestAnimationFrame(() => { requestAnimationFrame(step1) });
+};
 
-      // ClientRect members of IntersectionObserverEntry should be stable.
-      shouldEvaluateToSameObject("entries[0].boundingClientRect", entries[0].boundingClientRect);
-      shouldEvaluateToSameObject("entries[0].intersectionRect", entries[0].intersectionRect);
-      shouldEvaluateToSameObject("entries[0].rootBounds", entries[0].rootBounds);
+function step1() {
+  entries.push(...observer.takeRecords());
+  shouldBeEqualToNumber("entries.length", 1);
+  if (entries.length > 0) {
+    shouldBeEqualToNumber("entries[0].boundingClientRect.left", 8);
+    shouldBeEqualToNumber("entries[0].boundingClientRect.right", 8);
+    shouldBeEqualToNumber("entries[0].boundingClientRect.top", 408);
+    shouldBeEqualToNumber("entries[0].boundingClientRect.bottom", 408);
+    shouldBeEqualToNumber("entries[0].intersectionRect.left", 8);
+    shouldBeEqualToNumber("entries[0].intersectionRect.right", 8);
+    shouldBeEqualToNumber("entries[0].intersectionRect.top", 408);
+    shouldBeEqualToNumber("entries[0].intersectionRect.bottom", 408);
+    shouldBeEqualToNumber("entries[0].rootBounds.left", 0);
+    shouldBeEqualToNumber("entries[0].rootBounds.right", 785);
+    shouldBeEqualToNumber("entries[0].rootBounds.top", 0);
+    shouldBeEqualToNumber("entries[0].rootBounds.bottom", 600);
+    shouldEvaluateToSameObject("entries[0].target", target);
 
-      document.scrollingElement.scrollTop = 100;
-      requestAnimationFrame(step2);
-    });
+    // ClientRect members of IntersectionObserverEntry should be stable.
+    shouldEvaluateToSameObject("entries[0].boundingClientRect", entries[0].boundingClientRect);
+    shouldEvaluateToSameObject("entries[0].intersectionRect", entries[0].intersectionRect);
+    shouldEvaluateToSameObject("entries[0].rootBounds", entries[0].rootBounds);
   }
+  document.scrollingElement.scrollTop = 100;
+  requestAnimationFrame(step2);
+}
 
-  function step2() {
-    setTimeout(function() {
-      shouldBeEqualToNumber("entries.length", 2);
-      shouldBeEqualToNumber("entries[1].boundingClientRect.left", 8);
-      shouldBeEqualToNumber("entries[1].boundingClientRect.right", 8);
-      shouldBeEqualToNumber("entries[1].boundingClientRect.top", 608);
-      shouldBeEqualToNumber("entries[1].boundingClientRect.bottom", 608);
-      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", 0);
-      shouldBeEqualToNumber("entries[1].rootBounds.right", 785);
-      shouldBeEqualToNumber("entries[1].rootBounds.top", 0);
-      shouldBeEqualToNumber("entries[1].rootBounds.bottom", 600);
-      shouldEvaluateToSameObject("entries[1].target", target);
-      finishJSTest();
-      document.scrollingElement.scrollTop = 0;
-    });
+function step2() {
+  entries.push(...observer.takeRecords());
+  shouldBeEqualToNumber("entries.length", 2);
+  if (entries.length > 1) {
+    shouldBeEqualToNumber("entries[1].boundingClientRect.left", 8);
+    shouldBeEqualToNumber("entries[1].boundingClientRect.right", 8);
+    shouldBeEqualToNumber("entries[1].boundingClientRect.top", 608);
+    shouldBeEqualToNumber("entries[1].boundingClientRect.bottom", 608);
+    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", 0);
+    shouldBeEqualToNumber("entries[1].rootBounds.right", 785);
+    shouldBeEqualToNumber("entries[1].rootBounds.top", 0);
+    shouldBeEqualToNumber("entries[1].rootBounds.bottom", 600);
+    shouldEvaluateToSameObject("entries[1].target", target);
   }
-
+  finishJSTest();
+  document.scrollingElement.scrollTop = 0;
+}
 </script>