Import Cobalt 21.master.0.253153
diff --git a/src/third_party/web_platform_tests/intersection-observer/zero-area-element-visible.html b/src/third_party/web_platform_tests/intersection-observer/zero-area-element-visible.html
new file mode 100644
index 0000000..5431750
--- /dev/null
+++ b/src/third_party/web_platform_tests/intersection-observer/zero-area-element-visible.html
@@ -0,0 +1,40 @@
+<!DOCTYPE html>
+<meta name="viewport" content="width=device-width,initial-scale=1">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="./resources/intersection-observer-test-utils.js"></script>
+
+<style>
+pre, #log {
+ position: absolute;
+ top: 0;
+ left: 200px;
+}
+#target {
+ width: 0px;
+ height: 0px;
+}
+</style>
+
+<div id='target'></div>
+
+<script>
+var entries = [];
+
+runTestCycle(function() {
+ var target = document.getElementById('target');
+ assert_true(!!target, "target exists");
+ var observer = new IntersectionObserver(function(changes) {
+ entries = entries.concat(changes)
+ });
+ observer.observe(target);
+ entries = entries.concat(observer.takeRecords());
+ assert_equals(entries.length, 0, "No initial notifications.");
+ runTestCycle(step0, "First rAF should generate a notification.");
+}, "Ensure that a zero-area target intersecting root generates a notification with intersectionRatio == 1");
+
+function step0() {
+ assert_equals(entries.length, 1, "One notification.");
+ assert_equals(entries[0].intersectionRatio, 1, "intersectionRatio == 1");
+}
+</script>
