## Summary
Fixes https://github.com/facebook/react/issues/24781
Restricting from editing props, which are class instances, because their
internals should be opaque.
Proposed changes:
1. Adding new data type `class_instance`: based on prototype chain of an
object we will check if its plain or not. If not, then will be marked as
`class_instance`. This should not affect `arrays`, ..., because we do
this in the end of an `object` case in `getDataType` function.
Important detail: this approach won't work for objects created with
`Object.create`, because of the custom prototype. This can also be
bypassed by manually deleting a prototype ¯\\\_(ツ)_/¯
I am not sure if there might be a better solution (which will cover all
cases) to detect if object is a class instance. Initially I was trying
to use `Object.getPrototypeOf(object) === Object.prototype`, but this
won't work for cases when we are dealing with `iframe`.
2. Objects with a type `class_instance` will be marked as unserializable
and read-only.
## Demo
`person` is a class instance, `object` is a plain object
https://user-images.githubusercontent.com/28902667/228914791-ebdc8ab0-eb5c-426d-8163-66d56b5e8790.mov
It's confusing to new contributors, and me, that you're supposed to use
`yarn build-combined` for almost everything but not fixtures.
We should use only one build command for everything.
Updated fixtures to use the folder convention of build-combined.
The old version of prettier we were using didn't support the Flow syntax
to access properties in a type using `SomeType['prop']`. This updates
`prettier` and `rollup-plugin-prettier` to the latest versions.
I added the prettier config `arrowParens: "avoid"` to reduce the diff
size as the default has changed in Prettier 2.0. The largest amount of
changes comes from function expressions now having a space. This doesn't
have an option to preserve the old behavior, so we have to update this.