document.documentElement.scrollTop/Left is zero

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 235 matching lines @@
     if (zoomFactor == 1)
         return value;
     // Needed because of truncation (rather than rounding) when scaling up.
     if (zoomFactor > 1)
         value++;
     return static_cast<int>(value / zoomFactor);
 }
 
 int HTMLBodyElement::scrollLeft()
 {
+    if (!document().inQuirksMode())
+        return 0;
+
     // Update the document's layout.
     Document& document = this->document();
     document.updateLayoutIgnorePendingStylesheets();
     FrameView* view = document.view();
     return view ? adjustForZoom(view->scrollX(), &document) : 0;
 }
 
 void HTMLBodyElement::setScrollLeft(int scrollLeft)
 {
     Document& document = this->document();
     document.updateLayoutIgnorePendingStylesheets();
     Frame* frame = document.frame();
     if (!frame)
         return;
     FrameView* view = frame->view();
     if (!view)
         return;
     view->setScrollPosition(IntPoint(static_cast<int>(scrollLeft * frame->pageZoomFactor()), view->scrollY()));
 }
 
 int HTMLBodyElement::scrollTop()
 {
+    if (!document().inQuirksMode())
+        return 0;

[Julien - ping for review, 2013/09/30 23:39:57]

Is this totally correct?

Step 4 of scrollTop says: "Return the y-coordinate of the scrolling area at the
alignment point with the top of the padding edge of the element."

[tonikitoo_, 2013/10/01 14:42:17]

This is a valid observation! I believe the specification is not clear about
this, or it lacks a "return zero and terminate these steps" advice.

The way I implemented it makes Blink to match Firefox, IE, Safari nightly and
Opera (pre-blink) for this case, as it can be seen on
http://13thparallel.com/archive/viewport/example6.htm . Firefox implementation
is explicit about it:
http://lxr.mozilla.org/mozilla-central/source/content/base/src/Element.cpp#510 .

We could maybe chose to match other engines, and clarify with Hixie the spec.

[Julien - ping for review, 2013/10/01 15:19:51]

Clarifying the specification is definitely the way to go. It shouldn't block
this change though (you can put a comment linking to the thread or just a
FIXME).

+
     // Update the document's layout.
     Document& document = this->document();
     document.updateLayoutIgnorePendingStylesheets();
     FrameView* view = document.view();
     return view ? adjustForZoom(view->scrollY(), &document) : 0;
 }
 
 void HTMLBodyElement::setScrollTop(int scrollTop)
 {
     Document& document = this->document();
@@ skipping 26 matching lines @@
 }
 
 void HTMLBodyElement::addSubresourceAttributeURLs(ListHashSet<KURL>& urls) const
 {
     HTMLElement::addSubresourceAttributeURLs(urls);
 
     addSubresourceURL(urls, document().completeURL(getAttribute(backgroundAttr)));
 }
 
 } // namespace WebCore