our XML parsing of JNLP files is not robust enough. sometimes when JNLP files has syntax error, we did not report error and just ignore and continue. instead, we should report error to user instead.

e.g missing /> in <applet-desc> or <update>

see JIRA issue: http://javafx-jira.kenai.com/browse/RT-4843

Our JNLP XML parser should be able to catch these error and report to user; instead of ignoring the error and continue to launch.