SVG does not respect overflow:visible.

Source/core/rendering/svg/RenderSVGRoot.cpp

 /*
  * Copyright (C) 2004, 2005, 2007 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2004, 2005, 2007, 2008, 2009 Rob Buis <buis@kde.org>
  * Copyright (C) 2007 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2009 Google, Inc.
  * Copyright (C) Research In Motion Limited 2011. 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 213 matching lines @@
     m_overflow.clear();
     addVisualEffectOverflow();
     updateLayerTransform();
     m_hasBoxDecorations = isDocumentElement() ? calculateHasBoxDecorations() : hasBoxDecorations();
     invalidateBackgroundObscurationStatus();
 
     repainter.repaintAfterLayout();
     clearNeedsLayout();
 }
 
+bool RenderSVGRoot::shouldApplyViewportClip() const
+{
+    // the outermost svg is clipped if auto, and svg document roots are always clipped
+    // When the svg is standalone (isRoot() == true) the viewport clipping should always
+    // be applied, noting that the window scrollbars should be hidden if overflow=hidden.
+    return style()->overflowX() == OHIDDEN || style()->overflowX() == OAUTO || this->isRoot();

[fs, 2014/04/15 15:43:07]

isRoot() was recently renamed isDocumentElement(). (See for instance use above.)

[Erik Dahlström (inactive), 2014/04/16 15:53:49]

Fixed.

+}
+
 void RenderSVGRoot::paintReplaced(PaintInfo& paintInfo, const LayoutPoint& paintOffset)
 {
     // An empty viewport disables rendering.
     if (pixelSnappedBorderBoxRect().isEmpty())
         return;
 
     // Don't paint, if the context explicitly disabled it.
     if (paintInfo.context->paintingDisabled())
         return;
 
     // An empty viewBox also disables rendering.
     // (http://www.w3.org/TR/SVG/coords.html#ViewBoxAttribute)
     SVGSVGElement* svg = toSVGSVGElement(node());
     ASSERT(svg);
     if (svg->hasEmptyViewBox())
         return;
 
     // Don't paint if we don't have kids, except if we have filters we should paint those.
     if (!firstChild()) {
         SVGResources* resources = SVGResourcesCache::cachedResourcesForRenderObject(this);
         if (!resources || !resources->filter())
             return;
     }
 
     // Make a copy of the PaintInfo because applyTransform will modify the damage rect.
     PaintInfo childPaintInfo(paintInfo);
     childPaintInfo.context->save();
 
-    // Apply initial viewport clip - not affected by overflow handling
-    childPaintInfo.context->clip(pixelSnappedIntRect(overflowClipRect(paintOffset)));
+    // Apply initial viewport clip
+    if (shouldApplyViewportClip())
+        childPaintInfo.context->clip(pixelSnappedIntRect(overflowClipRect(paintOffset)));
 
     // Convert from container offsets (html renderers) to a relative transform (svg renderers).
     // Transform from our paint container's coordinate system to our local coords.
     IntPoint adjustedPaintOffset = roundedIntPoint(paintOffset);
     childPaintInfo.applyTransform(AffineTransform::translation(adjustedPaintOffset.x(), adjustedPaintOffset.y()) * localToBorderBoxTransform());
 
     // SVGRenderingContext must be destroyed before we restore the childPaintInfo.context, because a filter may have
     // changed the context and it is only reverted when the SVGRenderingContext destructor finishes applying the filter.
     {
         SVGRenderingContext renderingContext;
@@ skipping 95 matching lines @@
 
     // Return early for any cases where we don't actually paint.
     if (style()->visibility() != VISIBLE && !enclosingLayer()->hasVisibleContent())
         return LayoutRect();
 
     // Compute the repaint rect of the content of the SVG in the border-box coordinate space.
     FloatRect contentRepaintRect = repaintRectInLocalCoordinates();
     contentRepaintRect = m_localToBorderBoxTransform.mapRect(contentRepaintRect);
 
     // Apply initial viewport clip - not affected by overflow settings
     contentRepaintRect.intersect(pixelSnappedBorderBoxRect());

[fs, 2014/04/15 15:48:42]

This is a recent addition that also clips to the viewport - you may need to test
if you need the shouldApplyViewportClip() guard here (for things like moving the
entire SVG maybe.)

 
     LayoutRect repaintRect = enclosingLayoutRect(contentRepaintRect);
     // If the box is decorated or is overflowing, extend it to include the border-box and overflow.
     if (m_hasBoxDecorations || hasRenderOverflow()) {
         // The selectionRect can project outside of the overflowRect, so take their union
         // for repainting to avoid selection painting glitches.
         LayoutRect decoratedRepaintRect = unionRect(localSelectionRect(false), visualOverflowRect());
         repaintRect.unite(decoratedRepaintRect);
     }
 
     // Compute the repaint rect in the parent coordinate space.
     LayoutRect rect = enclosingIntRect(repaintRect);
     RenderReplaced::computeRectForRepaint(repaintContainer, rect);
     return rect;
 }
 
 void RenderSVGRoot::computeFloatRectForRepaint(const RenderLayerModelObject* repaintContainer, FloatRect& repaintRect, bool fixed) const
 {
     // Apply our local transforms (except for x/y translation), then our shadow,
     // and then call RenderBox's method to handle all the normal CSS Box model bits
     repaintRect = m_localToBorderBoxTransform.mapRect(repaintRect);
 
-    // Apply initial viewport clip - not affected by overflow settings
-    repaintRect.intersect(pixelSnappedBorderBoxRect());
+    // Apply initial viewport clip
+    if (shouldApplyViewportClip())
+        repaintRect.intersect(pixelSnappedBorderBoxRect());
 
     LayoutRect rect = enclosingIntRect(repaintRect);
     RenderReplaced::computeRectForRepaint(repaintContainer, rect, fixed);
     repaintRect = rect;
 }
 
 // This method expects local CSS box coordinates.
 // Callers with local SVG viewport coordinates should first apply the localToBorderBoxTransform
 // to convert from SVG viewport coordinates to local CSS box coordinates.
 void RenderSVGRoot::mapLocalToContainer(const RenderLayerModelObject* repaintContainer, TransformState& transformState, MapCoordinatesFlags mode, bool* wasFixed) const
@@ skipping 61 matching lines @@
 
 bool RenderSVGRoot::hasRelativeLogicalHeight() const
 {
     SVGSVGElement* svg = toSVGSVGElement(node());
     ASSERT(svg);
 
     return svg->intrinsicHeight(SVGSVGElement::IgnoreCSSProperties).isPercent();
 }
 
 }