Handling of unnamed package in javadoc pages

The package signature introduced in JDK-8245058 is broken for the unnamed package. I displays just the word "package" (see attached picture). The proper handling of the unnamed package would probably be to not display a package signature at all.

Also, the use of non-localized "<Unnamed>" as package name is questionable and should probably replaced by a localized string such as "Unnamed Package".