Containers with managed size and position should use contain:strict

[krassowski]

Description

Containers in some layouts (e.g. panels) have fully managed size and position but are slow to work with.

Reproduce

1. Open gh-9757-reproducer.ipynb and all-html-elements.ipynb notebooks as follows in a Chromium browser;
   
2. Try to resize split panel in top-bottom
3. See jitter

Without contain strict (current)	with contain:strict (proposed)

Expected behavior

No jitter on resize. Widget containers with managed size use contain: strict.