dillon1000/react

Replace shims with explicit React access from the renderers for shared global state (#9366)

* Remove non-existent /lib/ from souce files

* Replace all shims with explicit access

This deletes shims and changes to access require('react').__DO_NOT_USE__ from renderers for global shared state.

I cloned flattenChildren() and traverseAllChildren() because they relied on CurrentOwner but were used both from Stack and Isomorphic. The stack implementations will die, and the isomorphic ones can be changed to be optimized for Children specifically in the future.

I also deleted UMD shims because they are now unnecessary. I moved the internals assignment to main modules since they're now used in tests, and made them direct UMD entry points.