RFR: 8252936: Optimize removal of listeners from ExpressionHelper.Generic

[Nir Lisker]

On Mon, 24 Feb 2020 09:14:51 GMT, dannygonzalez <github.com+6702882+dannygonzalez at openjdk.org> wrote:

> So we need to keep the original behaviour from before where a count was checked on every addListener call and the weak references were purged from the array using the original calculation for this count.

The GC'd weak listeners do need to be purged, but why is the original behavior of the counters still applicable?

> We need to test against the entrySet.key not the entrySet itself.

I suggested to test against the elements in `keySet()`, which are the same as the ones in `entrySet().getKey()`.

-------------

PR: https://git.openjdk.java.net/jfx/pull/108