Layer Clear Selection is enabled even if nothing selected

[smalers]

This is high priority only because it is confusing to users.

See the following: http://poudre.openwaterfoundation.org/latest/#/map/current-drought

The popup menu Clear Selection is shown and is enabled. Can this be made disabled until something is actually selected? This seems to be an issue with all layer geometry types. Hopefully can just check whether a layer has an accompanying selection layer with > 0 features.