Propagate disabled state to descendants

[pieterdd]

This is a fix for Descendants of a disabled View apply disabled behavior, but not disabled styling. The code sample in that thread worked correctly for me after the code change:

For more context about why propagation of disabled state matters, see this example. The approach where classes are applied to child components and modified upon disabling of the parent doesn't work in all cases, plus it requires parent components to interfere with child components. Propagating the disabled state seemed like a better separation of concerns.

[dzhou121]

Thanks for the PR. But this approach is quite expensive.

I tried to fix it in e795021, can you please check if that works?

[pieterdd]

I'm happy to report that e795021 works correctly in all cases I tested. Thank you for the fix.