set and get scrollTop/Left through documentElement and body should be symmetric, according to the d…

Source/core/dom/Element.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Peter Kelly (pmk@post.com)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2007 David Smith (catfish.man@gmail.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012, 2013 Apple Inc. All rights reserved.
  *           (C) 2007 Eric Seidel (eric@webkit.org)
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 706 matching lines @@
     }
 
     if (RenderBox* rend = renderBox())
         return adjustForAbsoluteZoom(rend->scrollTop(), rend);
     return 0;
 }
 
 void Element::setScrollLeft(int newLeft)
 {
     document().updateLayoutIgnorePendingStylesheets();
+
+    if (document().documentElement() == this) {
+        if (document().inQuirksMode())
+            return;
+
+        Frame* frame = document().frame();
+        if (!frame)
+            return;
+        FrameView* view = frame->view();
+        if (!view)
+            return;
+        view->setScrollPosition(IntPoint(static_cast<int>(newLeft * frame->pageZoomFactor()), view->scrollY()));

[Julien - ping for review, 2013/10/05 01:05:46]

The specification is weird and seem to imply that you shouldn't put scrollY() as
the second parameter here:

"4. If the element is the root element invoke scroll() with x as first argument
and zero as second, and, if the given value is a ScrollOptionsHorizontal object,
the given value as the third argument."

Am I missing something obvious here?

+    }
+
     if (RenderBox* rend = renderBox())
         rend->setScrollLeft(static_cast<int>(newLeft * rend->style()->effectiveZoom()));
 }
 
 void Element::setScrollTop(int newTop)
 {
     document().updateLayoutIgnorePendingStylesheets();
+
+    if (document().documentElement() == this) {
+        if (document().inQuirksMode())
+            return;
+
+        Frame* frame = document().frame();
+        if (!frame)
+            return;
+        FrameView* view = frame->view();
+        if (!view)
+            return;
+        view->setScrollPosition(IntPoint(view->scrollX(), static_cast<int>(newTop * frame->pageZoomFactor())));
+    }
+
     if (RenderBox* rend = renderBox())
         rend->setScrollTop(static_cast<int>(newTop * rend->style()->effectiveZoom()));
 }
 
 int Element::scrollWidth()
 {
     document().updateLayoutIgnorePendingStylesheets();
     if (RenderBox* rend = renderBox())
         return adjustForAbsoluteZoom(rend->scrollWidth(), rend);
     return 0;
@@ skipping 2952 matching lines @@
     return 0;
 }
 
 Attribute* UniqueElementData::attributeItem(unsigned index)
 {
     ASSERT_WITH_SECURITY_IMPLICATION(index < length());
     return &m_attributeVector.at(index);
 }
 
 } // namespace WebCore