Preserve fractional scroll offset for JS scrolling API

Source/core/html/HTMLBodyElement.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Simon Hausmann (hausmann@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
@@ skipping 248 matching lines @@
         if (!document.inQuirksMode())
             return;
     }
 
     LocalFrame* frame = document.frame();
     if (!frame)
         return;
     FrameView* view = frame->view();
     if (!view)
         return;
-    view->setScrollPosition(IntPoint(static_cast<int>(scrollLeft * frame->pageZoomFactor()), view->scrollY()));
+    view->setScrollPosition(DoublePoint(scrollLeft * frame->pageZoomFactor(), view->scrollY()));
 }
 
 double HTMLBodyElement::scrollTop()
 {
     Document& document = this->document();
     document.updateLayoutIgnorePendingStylesheets();
 
     if (RuntimeEnabledFeatures::scrollTopLeftInteropEnabled()) {
         RenderBox* render = renderBox();
         if (!render)
@@ skipping 26 matching lines @@
         if (!document.inQuirksMode())
             return;
     }
 
     LocalFrame* frame = document.frame();
     if (!frame)
         return;
     FrameView* view = frame->view();
     if (!view)
         return;
-    view->setScrollPosition(IntPoint(view->scrollX(), static_cast<int>(scrollTop * frame->pageZoomFactor())));
+    view->setScrollPosition(DoublePoint(view->scrollX(), scrollTop * frame->pageZoomFactor()));
 }
 
 int HTMLBodyElement::scrollHeight()
 {
     // Update the document's layout.
     Document& document = this->document();
     document.updateLayoutIgnorePendingStylesheets();
     FrameView* view = document.view();
     return view ? adjustForZoom(view->contentsHeight(), &document) : 0;
 }
 
 int HTMLBodyElement::scrollWidth()
 {
     // Update the document's layout.
     Document& document = this->document();
     document.updateLayoutIgnorePendingStylesheets();
     FrameView* view = document.view();
     return view ? adjustForZoom(view->contentsWidth(), &document) : 0;
 }
 
 } // namespace blink