CC AnimationHost: Fix ProgrammaticScrollAnimator detach scope.

third_party/WebKit/LayoutTests/fast/scroll-behavior/resources/subframe-with-scroll.html

Index: third_party/WebKit/LayoutTests/fast/scroll-behavior/resources/subframe-with-scroll.html
diff --git a/third_party/WebKit/LayoutTests/fast/scroll-behavior/resources/subframe-with-scroll.html b/third_party/WebKit/LayoutTests/fast/scroll-behavior/resources/subframe-with-scroll.html
new file mode 100644
index 0000000000000000000000000000000000000000..fa56648a5f853fdae9e2acae3c46b804443f7d0e
--- /dev/null
+++ b/third_party/WebKit/LayoutTests/fast/scroll-behavior/resources/subframe-with-scroll.html
@@ -0,0 +1,31 @@
+<!DOCTYPE html>
+<html>
+<head>
+  <style>
+    #container {
+      width: 200px;
+      height: 200px;
+      overflow: scroll;
+    }
+    #content {
+      width: 750px;
+      height: 10000px;
+      background-color: blue;
+    }
+  </style>
+  <div id="container">
+    <div id="content"></div>
+  </div>
+  <script type="text/javascript">
+    if (window.internals)
+      internals.settings.setScrollAnimatorEnabled(true);
+
+    requestAnimationFrame(() => {
+      if (container.scrollTo)
+        container.scrollTo({left: 750, top: 10000, behavior: 'smooth'});
+      else
+        console.log('ERROR: no container.scrollTo');
+    });
+  </script>
+</head>
+</html>