SVG does not respect overflow:visible.

Source/core/rendering/svg/SVGRenderSupport.cpp

 /*
  * Copyright (C) 2007, 2008 Rob Buis <buis@kde.org>
  * Copyright (C) 2007 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2007 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2009 Google, Inc.  All rights reserved.
  * Copyright (C) 2009 Dirk Schulze <krit@webkit.org>
  * Copyright (C) Research In Motion Limited 2009-2010. 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
@@ skipping 265 matching lines @@
 }
 
 bool SVGRenderSupport::isOverflowHidden(const RenderObject* object)
 {
     // SVG doesn't support independent x/y overflow
     ASSERT(object->style()->overflowX() == object->style()->overflowY());
 
     // OSCROLL is never set for SVG - see StyleResolver::adjustRenderStyle
     ASSERT(object->style()->overflowX() != OSCROLL);
 
-    // RenderSVGRoot should never query for overflow state - it should always clip itself to the initial viewport size.
+    // RenderSVGRoot should never query for overflow state - it has special handling of 'auto'
     ASSERT(!object->isRoot());
 
     return object->style()->overflowX() == OHIDDEN;
 }
 
 void SVGRenderSupport::intersectRepaintRectWithResources(const RenderObject* renderer, FloatRect& repaintRect)
 {
     ASSERT(renderer);
 
     SVGResources* resources = SVGResourcesCache::cachedResourcesForRenderObject(renderer);
@@ skipping 100 matching lines @@
 }
 
 bool SVGRenderSupport::isRenderableTextNode(const RenderObject* object)
 {
     ASSERT(object->isText());
     // <br> is marked as text, but is not handled by the SVG rendering code-path.
     return object->isSVGInlineText() && !toRenderSVGInlineText(object)->hasEmptyText();
 }
 
 }