RFR: 8258777: SkinBase: add api to un-/register invalidation-/listChange listeners [v9]

[Kevin Rushforth]

On Mon, 12 Apr 2021 14:45:58 GMT, Jeanette Winzenburg <fastegal at openjdk.org> wrote:

>> Changes in Lambda..Handler:
>> - added api and implemenation to support invalidation and listChange listeners in the same way as changeListeners
>> - added java doc 
>> - added tests
>> 
>> Changes in SkinBase
>> - added api (and implementation delegating to the handler)
>> - copied java doc from the change listener un/register methods 
>> - added tests to verify that the new (and old) api is indeed delegating to the handler
>> 
>> Note that the null handling is slightly extended: all methods now can handle both null consumers (as before) and null observables (new) - this allows simplified code on rewiring "path" properties (see reference example in the issue)
>
> Jeanette Winzenburg has updated the pull request incrementally with one additional commit since the last revision:
> 
>   changed description as suggested in review

I filed [JDK-8265277](https://bugs.openjdk.java.net/browse/JDK-8265277) to add the missing `@since 9` javadoc tag.

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PR: https://git.openjdk.java.net/jfx/pull/409