Allow SVG images to not taint the canvas with drawImage/drawPattern

Source/core/svg/SVGAElement.cpp

 /*
  * Copyright (C) 2004, 2005, 2008 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2004, 2005, 2007 Rob Buis <buis@kde.org>
  * Copyright (C) 2007 Eric Seidel <eric@webkit.org>
  * Copyright (C) 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
  * version 2 of the License, or (at your option) any later version.
@@ skipping 117 matching lines @@
         SVGGraphicsElement::svgAttributeChanged(attrName);
         return;
     }
 
     SVGElementInstance::InvalidationGuard invalidationGuard(this);
 
     // Unlike other SVG*Element classes, SVGAElement only listens to SVGURIReference changes
     // as none of the other properties changes the linking behaviour for our <a> element.
     if (SVGURIReference::isKnownAttribute(attrName)) {
         bool wasLink = isLink();
-        setIsLink(!hrefCurrentValue().isNull());
+        setIsLink(!hrefCurrentValue().isNull() && !shouldProhibitLinks(this));
 
         if (wasLink != isLink())
             setNeedsStyleRecalc();
     }
 }
 
 RenderObject* SVGAElement::createRenderer(RenderStyle*)
 {
     if (parentNode() && parentNode()->isSVGElement() && toSVGElement(parentNode())->isTextContent())
         return new RenderSVGInline(this);
@@ skipping 86 matching lines @@
     // The 'a' element may contain any element that its parent may contain, except itself.
     if (childContext.node()->hasTagName(SVGNames::aTag))
         return false;
     if (parentNode() && parentNode()->isSVGElement())
         return parentNode()->childShouldCreateRenderer(childContext);
 
     return SVGElement::childShouldCreateRenderer(childContext);
 }
 
 } // namespace WebCore