IntersectionObserver: second cut.

third_party/WebKit/Source/core/dom/IntersectionObserverEntry.idl

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// https://github.com/slightlyoff/IntersectionObserver
+
+[
+    GarbageCollected,
+    RuntimeEnabled=IntersectionObserver,
+] interface IntersectionObserverEntry {
+    readonly attribute ClientRect boundingClientRect;
+    readonly attribute ClientRect intersectionRect;
+    readonly attribute ClientRect rootBounds;
+    readonly attribute Element target;
+    readonly attribute DOMHighResTimeStamp time;
+};