[Maps] Fit to data on heatmap not working

[nickofthyme]

Kibana version:
7.12

Elasticsearch version:
7.12

Browser version:
Chrome Version 88.0.4324.150 (Official Build) (x86_64)

Original install method (e.g. download page, yum, from source, etc.):
build candidate tar.gz

Describe the bug:
Using a heatmap layer in maps, clicking fit data does not work

Steps to reproduce:

1. Download sample flight data
2. Add filter for DestCountry : "IT"
3. Zoom out
4. Click Fit to data on layer options dropdown
5. Notice nothing happens

Expected behavior:
Zoom is set by data

Screenshots (if relevant):

Screen.Recording.2021-02-22.at.03.29.33.PM.mp4

Errors in browser console (if relevant):
N/A

Any additional context:
Fit to data works fine on other layers in same map, see screenshot

[elasticmachine]

Pinging @elastic/kibana-gis (Team:Geo)

[thomasneirynck]

thx for logging, I can reproduce on master.

[nreese]

I can fix. Its a regression caused by #90666. That PR changed HeatmapLayer from extending VectorLayer to just extending AbstractLayer. Looks like getBounds needs to be implemented for HeatmapLayer.