IntersectionObserver: Always send an initial notification.

third_party/WebKit/LayoutTests/intersection-observer/timestamp.html

Index: third_party/WebKit/LayoutTests/intersection-observer/timestamp.html
diff --git a/third_party/WebKit/LayoutTests/intersection-observer/timestamp.html b/third_party/WebKit/LayoutTests/intersection-observer/timestamp.html
index 6667f546c4831a54e5ff91d1175d3e569f3541c7..f88ce912ef0c1eea2ab7b10bc77c09955e59d1c2 100644
--- a/third_party/WebKit/LayoutTests/intersection-observer/timestamp.html
+++ b/third_party/WebKit/LayoutTests/intersection-observer/timestamp.html
@@ -67,8 +67,8 @@ function step1() {
   topWindowTimeBeforeNotification = performance.now();
   iframeWindowTimeBeforeNotification = targetIframe.contentWindow.performance.now();
   runTestCycle(step2, "Generate notifications.");
-  assert_equals(topWindowEntries.length, 0, "No notifications to top window observer.");
-  assert_equals(iframeWindowEntries.length, 0, "No notifications to iframe observer.");
+  assert_equals(topWindowEntries.length, 1, "One notification to top window observer.");
+  assert_equals(iframeWindowEntries.length, 1, "One notification to iframe observer.");
 }
 
 function step2() {
@@ -81,16 +81,16 @@ function step2() {
   assert_greater_than(topWindowTimeBeforeNotification, iframeWindowTimeAfterNotification,
 		      "Time ranges for top and iframe windows are disjoint.");
 
-  assert_equals(topWindowEntries.length, 1, "Top window observer has one notification.");
+  assert_equals(topWindowEntries.length, 2, "Top window observer has two notifications.");
   assert_between_inclusive(
-      topWindowEntries[0].time,
+      topWindowEntries[1].time,
       topWindowTimeBeforeNotification,
       topWindowTimeAfterNotification,
       "Notification to top window observer is within the expected range.");
 
-  assert_equals(iframeWindowEntries.length, 1, "Iframe observer has one notification.");
+  assert_equals(iframeWindowEntries.length, 2, "Iframe observer has two notifications.");
   assert_between_inclusive(
-      iframeWindowEntries[0].time,
+      iframeWindowEntries[1].time,
       iframeWindowTimeBeforeNotification,
       iframeWindowTimeAfterNotification,
       "Notification to iframe observer is within the expected range.");