Make it clear to get m_svgExtensions using svgExtensions().
https://bugs.webkit.org/show_bug.cgi?id=134186.

Patch by Jeongeun Kim <je_julie.kim@samsung.com> on 2014-06-23
Reviewed by Dirk Schulze.

This patch makes sure that the purpose of code is to get m_svgExtensions
as changing accessSVGExtensions() to svgExtensions().
svgExtensions() is a getter API and accessSVGExtensions() checks
the presence of m_svgExtensions and create m_svgExtensions if it does not exist.

No new tests, no behavior change.

* dom/ContainerNode.cpp:
(WebCore::ContainerNode::removeChild):
(WebCore::ContainerNode::removeChildren):
* dom/Document.cpp:
(WebCore::Document::commonTeardown):
(WebCore::Document::implicitClose):
* history/CachedFrame.cpp:
(WebCore::CachedFrameBase::restore):
* svg/SVGDocumentExtensions.cpp:
(WebCore::SVGDocumentExtensions::startAnimations):
(WebCore::SVGDocumentExtensions::pauseAnimations):
(WebCore::SVGDocumentExtensions::unpauseAnimations):
(WebCore::SVGDocumentExtensions::dispatchSVGLoadEventToOutermostSVGElements):
(WebCore::SVGDocumentExtensions::rebuildElements):
* svg/SVGDocumentExtensions.h:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@170287 268f45cc-cd09-0410-ab3c-d52691b4dbfc