Have Document::accessSVGExtensions() return a reference

Source/core/svg/SVGAnimateElement.cpp

Index: Source/core/svg/SVGAnimateElement.cpp
diff --git a/Source/core/svg/SVGAnimateElement.cpp b/Source/core/svg/SVGAnimateElement.cpp
index c02ef6b60718c1ad1a1dae7bed1d446382417c8d..29b7a9763744724bf14e6cff520a6bba670e4c0a 100644
--- a/Source/core/svg/SVGAnimateElement.cpp
+++ b/Source/core/svg/SVGAnimateElement.cpp
@@ -206,7 +206,7 @@ void SVGAnimateElement::resetAnimatedType()
         m_animatedProperties = animator->findAnimatedPropertiesForAttributeName(targetElement, attributeName);
         SVGElementAnimatedPropertyList::const_iterator end = m_animatedProperties.end();
         for (SVGElementAnimatedPropertyList::const_iterator it = m_animatedProperties.begin(); it != end; ++it)
-            document().accessSVGExtensions()->addElementReferencingTarget(this, it->element);
+            document().accessSVGExtensions().addElementReferencingTarget(this, it->element);
 
         ASSERT(!m_animatedProperties.isEmpty());