RFR: 8220217: Javadoc missing link to member method

[Hannes Wallnöfer]

Please review:

JBS: https://bugs.openjdk.java.net/browse/JDK-8220217
Webrev: http://cr.openjdk.java.net/~hannesw/8220217/webrev.00/

The problem was that Utils.isLinkable(TypeElement, Element) was checking for subtype relationship to detect members inherited from undocumented supertypes, which fails when a subclass uses a parameterized version of a generic superclass as that breaks the subtype relationship. My solution is to move the isUndocumentedEnclosure(TypeElement) method from VisibleMemberTable to the Utils class and use it instead of the subclass check in Utils.isLinkable.

Thanks,
Hannes