Replace various ScrollableArea scroll methods with setScrollPosition

Source/platform/scroll/ScrollTypes.h

Index: Source/platform/scroll/ScrollTypes.h
diff --git a/Source/platform/scroll/ScrollTypes.h b/Source/platform/scroll/ScrollTypes.h
index 89d11727b2af8019e0d30a01d7e36715e5762b2e..c3a75baaf8d7347e88f2edb27db4f96257cb6f3e 100644
--- a/Source/platform/scroll/ScrollTypes.h
+++ b/Source/platform/scroll/ScrollTypes.h
@@ -49,6 +49,12 @@ enum ScrollDirectionPhysical {
     ScrollRight
 };
 
+enum ScrollType {
+    UserScroll,
+    ProgrammaticScroll,
+    CompositorScroll
+};
+
 // Convert logical scroll direction to physical. Physical scroll directions are unaffected.
 inline ScrollDirectionPhysical toPhysicalDirection(ScrollDirection direction, bool isVertical, bool isFlipped)
 {