Preserve fractional scroll offset for JS scrolling API

Source/platform/scroll/ScrollableArea.h

Index: Source/platform/scroll/ScrollableArea.h
diff --git a/Source/platform/scroll/ScrollableArea.h b/Source/platform/scroll/ScrollableArea.h
index 23d846071e8a9c4af477b59b8373b247fa13974e..10eac6fa1cd1ef6b1c93699575fda11a634d6bc4 100644
--- a/Source/platform/scroll/ScrollableArea.h
+++ b/Source/platform/scroll/ScrollableArea.h
@@ -264,7 +264,8 @@ private:
     // call into the IntPoint version. If fractional scroll is needed, one
     // can override the DoublePoint version to take advantage of the double
     // precision scroll offset.
-    // FIXME: Remove the IntPoint version. crbug.com/414283.
+    // FIXME: Remove the IntPoint version. And change the function to
+    // take DoubleSize. crbug.com/414283.
     virtual void setScrollOffset(const IntPoint&) = 0;
     virtual void setScrollOffset(const DoublePoint& offset)
     {