(JBIDE-13400) PageContextFactory.ExtendedLinkElementAdapter is leaked

The issue is fixed by avoiding the adding of ExtendedLinkElementAdapter to the nodes.
ExtendedLinkElementAdapter is used only on a temporary basis and as such no leaks should occur.

	modified:   plugins/org.jboss.tools.jst.css/src/org/jboss/tools/jst/css/dialog/selector/model/CSSJSPRecognizer.java
	modified:   plugins/org.jboss.tools.jst.css/src/org/jboss/tools/jst/css/dialog/selector/model/CSSSelectorTreeModel.java
	modified:   plugins/org.jboss.tools.jst.text.ext/src/org/jboss/tools/jst/text/ext/hyperlink/CSSClassHyperlink.java
	modified:   plugins/org.jboss.tools.jst.web.kb/src/org/jboss/tools/jst/web/kb/PageContextFactory.java
	modified:   plugins/org.jboss.tools.jst.web.kb/src/org/jboss/tools/jst/web/kb/internal/proposal/CSSClassProposalType.java