Structured error display

I had an exception, and I was in devtools, and it would have been super useful to be able to inspect the various objects mentioned in the structured error message.

Especially useful would have been the ability to inspect the properties of the objects, and be able to jump to the corresponding render objects in the inspector view.

This is probably a medium-priority feature request. In particular, if we don't have this feature, it draws into question why we bother having structured error messages at all; if the feature is no longer deemed useful, we should simplify the framework code by removing all the logic around structured errors.

Start by tracing how DevTools displays structured error messages and how the inspector view represents render objects. Determine how object properties and corresponding render objects could be exposed for inspection; done means structured errors support both capabilities without removing their existing purpose.

Written by the indexing model from the issue text.