Marquee width should not change a fixed width of its container.

Source/core/layout/LayoutBlock.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2007 David Smith (catfish.man@gmail.com)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) Research In Motion Limited 2010. 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 1989 matching lines @@
 {
     if (childrenInline()) {
         // FIXME: Remove this const_cast.
         toLayoutBlockFlow(const_cast<LayoutBlock*>(this))->computeInlinePreferredLogicalWidths(minLogicalWidth, maxLogicalWidth);
     } else {
         computeBlockPreferredLogicalWidths(minLogicalWidth, maxLogicalWidth);
     }
 
     maxLogicalWidth = std::max(minLogicalWidth, maxLogicalWidth);
 
+    if (!styleRef().autoWrap() && layer() && isHTMLMarqueeElement(node())) {

[mstensho (USE GERRIT), 2015/06/23 09:33:30]

What's with the layer() check?

Also not sure why we need the !styleRef().autoWrap() check.
HTMLMarqueeElement.js controls sets the white-space property on the MARQUEE
element (nowrap for horizontal marquees). If the document overrides this to get
a broken marquee, who cares?

[changseok, 2015/06/24 06:15:58]

This is garbage code. This change is inspired by webkit code. It checks if a
render block is a marquee through RenderLayer so it needs to check a layer
existence first. But we don't need to do because we manipulate the marquee with
a shadow root as you said, the layer has no way to check if a layout object is
marquee or not.
You're right, That was a redundant check for direction.

+        AtomicString direction = toElement(node())->getAttribute(directionAttr);

[mstensho (USE GERRIT), 2015/06/23 09:33:31]

I think I'd like to see this logic being moved to HTMLMarqueeElement. Add an
HTMLMarqueeElement::isHorizontalMarquee()?

[changseok, 2015/06/24 06:15:58]

OK

+        if (direction != "down" && direction != "up")
+            minLogicalWidth = 0;
+    }
+
     if (isTableCell()) {
         Length tableCellWidth = toLayoutTableCell(this)->styleOrColLogicalWidth();
         if (tableCellWidth.isFixed() && tableCellWidth.value() > 0)
             maxLogicalWidth = std::max(minLogicalWidth, adjustContentBoxLogicalWidthForBoxSizing(tableCellWidth.value()));
     }
 
     int scrollbarWidth = intrinsicScrollbarLogicalWidth();
     maxLogicalWidth += scrollbarWidth;
     minLogicalWidth += scrollbarWidth;
 }
@@ skipping 897 matching lines @@
 void LayoutBlock::showLineTreeAndMark(const InlineBox* markedBox1, const char* markedLabel1, const InlineBox* markedBox2, const char* markedLabel2, const LayoutObject* obj) const
 {
     showLayoutObject();
     for (const RootInlineBox* root = firstRootBox(); root; root = root->nextRootBox())
         root->showLineTreeAndMark(markedBox1, markedLabel1, markedBox2, markedLabel2, obj, 1);
 }
 
 #endif
 
 } // namespace blink