Use float for scroll offset.

third_party/WebKit/Source/core/paint/PaintLayerClipper.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
  *   Randall Jesup <rjesup@wgate.com>
@@ skipping 59 matching lines @@
 static void applyClipRects(const ClipRectsContext& context,
                            const LayoutBoxModelObject& layoutObject,
                            LayoutPoint offset,
                            ClipRects& clipRects) {
   DCHECK(layoutObject.hasClipRelatedProperty() ||
          (layoutObject.isSVGRoot() &&
           toLayoutSVGRoot(&layoutObject)->shouldApplyViewportClip()));
   LayoutView* view = layoutObject.view();
   DCHECK(view);
   if (clipRects.fixed() && context.rootLayer->layoutObject() == view)
-    offset -= toIntSize(view->frameView()->scrollPosition());
+    offset -= LayoutSize(view->frameView()->scrollOffset());
   if (layoutObject.hasOverflowClip() ||
       (layoutObject.isSVGRoot() &&
        toLayoutSVGRoot(&layoutObject)->shouldApplyViewportClip()) ||
       (layoutObject.styleRef().containsPaint() && layoutObject.isBox())) {
     ClipRect newOverflowClip =
         toLayoutBox(layoutObject)
             .overflowClipRect(offset, context.overlayScrollbarClipBehavior);
     newOverflowClip.setHasRadius(layoutObject.styleRef().hasBorderRadius());
     clipRects.setOverflowClipRect(
         intersection(newOverflowClip, clipRects.overflowClipRect()));
@@ skipping 242 matching lines @@
     m_layer.parent()->clipper().getOrCalculateClipRects(context,
                                                         *parentClipRects);
 
   ClipRect result = backgroundClipRectForPosition(
       *parentClipRects, m_layer.layoutObject()->styleRef().position());
 
   // Note: infinite clipRects should not be scrolled here, otherwise they will accidentally no longer be considered infinite.
   if (parentClipRects->fixed() &&
       context.rootLayer->layoutObject() == layoutView &&
       result != LayoutRect(LayoutRect::infiniteIntRect()))
-    result.move(toIntSize(layoutView->frameView()->scrollPosition()));
+    result.move(LayoutSize(layoutView->frameView()->scrollOffset()));
 
   return result;
 }
 
 void PaintLayerClipper::getOrCalculateClipRects(const ClipRectsContext& context,
                                                 ClipRects& clipRects) const {
   if (context.usesCache())
     clipRects = getClipRects(context);
   else
     calculateClipRects(context, clipRects);
@@ skipping 19 matching lines @@
     ShouldRespectOverflowClipType respectOverflowClip,
     const LayoutSize& subpixelAccumulation) const {
   ClipRectsContext context(rootLayer, PaintingClipRects,
                            IgnoreOverlayScrollbarSize, subpixelAccumulation);
   if (respectOverflowClip == IgnoreOverflowClip)
     context.setIgnoreOverflowClip();
   return getClipRects(context);
 }
 
 }  // namespace blink