Remove ScrollableArea::notifyScrollPositionChanged and cleanup scroll animators.

Source/core/paint/DeprecatedPaintLayerScrollableArea.cpp

Index: Source/core/paint/DeprecatedPaintLayerScrollableArea.cpp
diff --git a/Source/core/paint/DeprecatedPaintLayerScrollableArea.cpp b/Source/core/paint/DeprecatedPaintLayerScrollableArea.cpp
index 5e87c93f3ca5fa06a7f82f8dcb3e4b9397236621..18589dfea6f4fcc6ab4250ea2140223b9644c309 100644
--- a/Source/core/paint/DeprecatedPaintLayerScrollableArea.cpp
+++ b/Source/core/paint/DeprecatedPaintLayerScrollableArea.cpp
@@ -635,10 +635,7 @@ void DeprecatedPaintLayerScrollableArea::updateAfterLayout()
 
     if (originalScrollOffset != adjustedScrollOffset()) {
         DoublePoint origin(scrollOrigin());
-
-        // Call the base version here since calling this class' version will early because the
-        // offset itself hasn't changed, the scroll origin has.
-        ScrollableArea::setScrollPosition(-origin + adjustedScrollOffset(), ProgrammaticScroll);
+        scrollPositionChanged(-origin + adjustedScrollOffset(), ProgrammaticScroll);
     }
 
     bool hasHorizontalOverflow = this->hasHorizontalOverflow();