JBIDE-16432 Content assist for ns jsf/facelets is broken on the last line in xhtml file

Issue is fixed
JUnit Test is added cor the issue: org.jboss.tools.jst.web.ui.editor.test.ca.JstJspCANamespacesInLastChar

Signed-off-by: vrubezhny <vrubezhny@exadel.com>