Method DepthTracker

3rdparty/tinyxml2/tinyxml2.h:1970–1973

	class DepthTracker {
	public:
		explicit DepthTracker(XMLDocument * document) {
			this->_document = document;
			document->PushDepth();
		}
		~DepthTracker() {
			_document->PopDepth();
		}