Make composited scrolling codepaths co-operate.

Source/web/tests/ScrollingCoordinatorChromiumTest.cpp

Index: Source/web/tests/ScrollingCoordinatorChromiumTest.cpp
diff --git a/Source/web/tests/ScrollingCoordinatorChromiumTest.cpp b/Source/web/tests/ScrollingCoordinatorChromiumTest.cpp
index 9c6e80cd5f14398e223bd983fff891c3d980b8d7..e5837f5ff371c3168aa71637bf0bab259e109efc 100644
--- a/Source/web/tests/ScrollingCoordinatorChromiumTest.cpp
+++ b/Source/web/tests/ScrollingCoordinatorChromiumTest.cpp
@@ -254,8 +254,7 @@ TEST_F(ScrollingCoordinatorChromiumTest, nonFastScrollableRegion)
     WebLayer* rootScrollLayer = getRootScrollLayer();
     WebVector<WebRect> nonFastScrollableRegion = rootScrollLayer->nonFastScrollableRegion();
 
-    ASSERT_EQ(1u, nonFastScrollableRegion.size());
-    ASSERT_EQ(WebRect(8, 8, 10, 10), nonFastScrollableRegion[0]);
+    ASSERT_EQ(0u, nonFastScrollableRegion.size());
 }
 
 TEST_F(ScrollingCoordinatorChromiumTest, wheelEventHandler)