Memory leak keeps growing when mounting / unmounting elements

[AlexAtlas]

Hi, I was running this repo and playing around with the widgets demo, and I noticed that when I was mounting / unmounting elements ( opening and closing elements like the calendar / colour picker), the amount of memory leak kept growing and growing ? this seems like a big issue ? is this a known issue and can it maybe get fixed by altering the reconciler file ?

Steps to reproduce.

1. run the widget demo.

2. Close the demo immediately

3. check the memory leak log

4. run the widget demo again

5. repeatedly open and close the colour picker

6. Close the demo.

7. See that the memory leak / in blocks has increased
   

[derekstavis]

I spent quite some time trying to trace down some of these leaks but I haven't been able to find them. I can take a look at the calendar implementation, but if you'd like to help identifying all the leaks, building a demo that helps to test and isolate leaks would be welcome