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 2d4b06e0b8b4871964320f7a39ba093fe31fdf02..b8c18e7d2a90ca973de3cdea63e160892187bd95 100644
--- a/third_party/WebKit/Source/platform/scroll/ScrollableArea.cpp
+++ b/third_party/WebKit/Source/platform/scroll/ScrollableArea.cpp
@@ -383,11 +383,9 @@ void ScrollableArea::contentsResized() {
 }
 
 bool ScrollableArea::hasOverlayScrollbars() const {
-  Scrollbar* vScrollbar = verticalScrollbar();
-  if (vScrollbar && vScrollbar->isOverlayScrollbar())
-    return true;
-  Scrollbar* hScrollbar = horizontalScrollbar();
-  return hScrollbar && hScrollbar->isOverlayScrollbar();
+  return (horizontalScrollbar() &&
+          horizontalScrollbar()->isOverlayScrollbar()) ||
+         (verticalScrollbar() && verticalScrollbar()->isOverlayScrollbar());
 }
 
 void ScrollableArea::setScrollbarOverlayColorTheme(