Propagate update in `functionselect.js`  in `selectChanged` instead of `function.selected`'s watcher
Propagate update in `functionselect.js`  in `selectChanged` instead of `function.selected`'s watcher

cc: da39a3ee5e6b4b0d3255bfef95601890afd80709@zeningqu  -- I've tested this briefly and it seems correct.  Can you double check?

uwdata/vega-lite-ui,uwdata/vega-lite-ui,vega/vega-lite-ui,vega/vega-lite-ui,uwdata/vega-lite-ui,vega/vega-lite-ui