Revert "MainFrame scrollbars should work with RFV instead of FV"

third_party/WebKit/Source/platform/scroll/ScrollableArea.cpp

Index: third_party/WebKit/Source/platform/scroll/ScrollableArea.cpp
diff --git a/third_party/WebKit/Source/platform/scroll/ScrollableArea.cpp b/third_party/WebKit/Source/platform/scroll/ScrollableArea.cpp
index 5ee4df68b5d0452c49eb237e9ba2df00dfcb3288..838c8e3f314f346598e67d1281c898a969e5406e 100644
--- a/third_party/WebKit/Source/platform/scroll/ScrollableArea.cpp
+++ b/third_party/WebKit/Source/platform/scroll/ScrollableArea.cpp
@@ -389,9 +389,11 @@ void ScrollableArea::contentsResized() {
 }
 
 bool ScrollableArea::hasOverlayScrollbars() const {
-  return (horizontalScrollbar() &&
-          horizontalScrollbar()->isOverlayScrollbar()) ||
-         (verticalScrollbar() && verticalScrollbar()->isOverlayScrollbar());
+  Scrollbar* vScrollbar = verticalScrollbar();
+  if (vScrollbar && vScrollbar->isOverlayScrollbar())
+    return true;
+  Scrollbar* hScrollbar = horizontalScrollbar();
+  return hScrollbar && hScrollbar->isOverlayScrollbar();
 }
 
 void ScrollableArea::setScrollbarOverlayColorTheme(