Fix scrollbar damage accumulation issue

Source/core/frame/FrameView.cpp

Index: Source/core/frame/FrameView.cpp
diff --git a/Source/core/frame/FrameView.cpp b/Source/core/frame/FrameView.cpp
index 76d637ddf702cd4b2734182745896b63e426379b..9dda0b78d2daa9febf173c629ae0e45f484c5569 100644
--- a/Source/core/frame/FrameView.cpp
+++ b/Source/core/frame/FrameView.cpp
@@ -2344,17 +2344,10 @@ void FrameView::invalidateScrollbarRect(Scrollbar* scrollbar, const IntRect& rec
     IntRect dirtyRect = rect;
     dirtyRect.moveBy(scrollbar->location());
 
-    if (isInPerformLayout()) {
-        if (scrollbar == verticalScrollbar()) {
-            m_verticalBarDamage = dirtyRect;
-            m_hasVerticalBarDamage = true;
-        } else {
-            m_horizontalBarDamage = dirtyRect;
-            m_hasHorizontalBarDamage = true;
-        }
-    } else {
+    if (isInPerformLayout())
+        addScrollbarDamage(scrollbar, rect);
+    else
         invalidateRect(dirtyRect);
-    }
 }
 
 void FrameView::getTickmarks(Vector<IntRect>& tickmarks) const