Use float for scroll offset.

third_party/WebKit/Source/core/layout/LayoutFlexibleBox.cpp

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 378 matching lines @@
 
   m_relaidOutChildren.clear();
 
   if (updateLogicalWidthAndColumnWidth())
     relayoutChildren = true;
 
   SubtreeLayoutScope layoutScope(*this);
   LayoutUnit previousHeight = logicalHeight();
   setLogicalHeight(borderAndPaddingLogicalHeight() + scrollbarLogicalHeight());
 
-  PaintLayerScrollableArea::DelayScrollPositionClampScope delayClampScope;
+  PaintLayerScrollableArea::DelayScrollOffsetClampScope delayClampScope;
 
   {
     TextAutosizer::LayoutScope textAutosizerLayoutScope(this, &layoutScope);
     LayoutState state(*this, locationOffset());
 
     m_numberOfInFlowChildrenOnFirstLine = -1;
 
     prepareOrderIteratorAndMargins();
 
     layoutFlexItems(relayoutChildren, layoutScope);
@@ skipping 1875 matching lines @@
       LayoutUnit originalOffset =
           lineContexts[lineNumber].crossAxisOffset - crossAxisStartEdge;
       LayoutUnit newOffset =
           contentExtent - originalOffset - lineCrossAxisExtent;
       adjustAlignmentForChild(*child, newOffset - originalOffset);
     }
   }
 }
 
 }  // namespace blink