Deflake virtual/threaded/fast/scroll-behavior/smooth-scroll/ongoing-smooth-scroll-vertical-rl-ancho…

third_party/WebKit/LayoutTests/fast/scroll-behavior/smooth-scroll/ongoing-smooth-scroll-vertical-rl-anchors.html

Index: third_party/WebKit/LayoutTests/fast/scroll-behavior/smooth-scroll/ongoing-smooth-scroll-vertical-rl-anchors.html
diff --git a/third_party/WebKit/LayoutTests/fast/scroll-behavior/smooth-scroll/ongoing-smooth-scroll-vertical-rl-anchors.html b/third_party/WebKit/LayoutTests/fast/scroll-behavior/smooth-scroll/ongoing-smooth-scroll-vertical-rl-anchors.html
index 5c8d642f3355a35f326267ae4cb6d72385500d72..14b6a1a58b660a70fb4a365ef69142268d3f497b 100644
--- a/third_party/WebKit/LayoutTests/fast/scroll-behavior/smooth-scroll/ongoing-smooth-scroll-vertical-rl-anchors.html
+++ b/third_party/WebKit/LayoutTests/fast/scroll-behavior/smooth-scroll/ongoing-smooth-scroll-vertical-rl-anchors.html
@@ -11,7 +11,7 @@
   }
   #changer {
     background-color: #FF7F7F;
-    width: 0px;
+    width: 10px;
   }
   #anchor {
     width: 1500px;
@@ -23,15 +23,18 @@
 <div id="anchor"></div>
 
 <script>
-  var asyncTest = async_test("Verify smooth scroll interaction with scroll anchroing on page with vertical-lr writing mode");
+  var asyncTest = async_test("Verify smooth scroll interaction with scroll anchoring on page with vertical-lr writing mode");
 
   // The element that will change in height.
   var ch;
+  // Initital scroll position.
+  var initialX = -10;
+  var initialY = 0;
   // Amount to smooth scroll by.
   var userScrollX = -205;
   var userScrollY = 51;
   // Amount to change the height of the element above the viewport.
-  var changerX =  100;
+  var changerX = 100;
   // End position: height of ch + userScroll.
   var endX = -305;
   var endY = 51;
@@ -53,11 +56,17 @@
     internals.settings.setScrollAnimatorEnabled(true);
 
     ch = document.getElementById("changer");
+    window.scrollTo(initialX, initialY);
 
-    // Smooth scroll.
-    eventSender.mouseMoveTo(100, 100);
-    eventSender.continuousMouseScrollBy(-userScrollX, -userScrollY);
+    asyncTest.step(function() {
+      assert_equals(window.scrollX, initialX);
+      assert_equals(window.scrollY, initialY);
 
-    document.addEventListener("scroll", scrollListener);
+      // Smooth scroll.
+      eventSender.mouseMoveTo(100, 100);
+      eventSender.continuousMouseScrollBy(-userScrollX, -userScrollY);
+
+      document.addEventListener("scroll", scrollListener);
+    });
   }
 </script>