IZ 166411: Wrong icon for method arguments or method return value in Variables window

http://www.netbeans.org/issues/show_bug.cgi?id=166411

Description: Wrong icon is displayed for method arguments or method 
return value in Variables window.

Impact: Looks like there's an error, an exclamation mark in a yellow 
triangle appears. It's visible and very confusing for users.

Risk assessment: No risk, the fix is very save. Just the reference to 
the original icon is returned.

Peer review at http://www.netbeans.org/issues/show_bug.cgi?id=166411#desc4

Changeset: http://hg.netbeans.org/main/rev/800ee0dc4211

Thanks,
Martin