Ref https://github.com/webstudio-is/webstudio/issues/1536https://github.com/webstudio-is/webstudio/issues/3399
Here added very basic setup for style object model. Computed all
normalized data with "computed" store.
It will let us to integrate style object model
into a few controls and test new engine.
Instance selector now is an input for getComputedStyleDecl to allow
looking into parent styles, like we do for flex child.