7.0.1 HR fix for #199194: Handling of javadoc generated by (Open)JDK1.7

http://netbeans.org/bugzilla/show_bug.cgi?id=199194
http://hg.netbeans.org/main-golden/rev/cdba185ee45a

The exception in the log that is being fixed by this fix means that HTML 
javadoc cannot be parsed correctly. This means that the javadoc is not 
shown in the code completion and the parameter names may be missing. 
This occurs when sources are not attached to the given library/platform 
and HTML javadoc is attached to it.

The new code should only be triggered by the new HTML javadoc, so the 
fix should be relatively safe.

The patch has been reviewed by dbalek (dev) and stezeb (QE).

Thanks,
    Jan