dillon1000/react

Simple updates using alternate fibers

This splits the Fiber type into Fiber and Instance. This could be
two different object instances to save memory. However, to avoid
GC thrash I merge them into one.

When ReactChildFiber reconciles children, it clones the previous
fiber. This creates a new tree for work-in-progress. The idea is
that once flushed, this new tree will be used at the root.

However, we know that we'll never need more than two trees
at a time. Therefore my clone function stores the clone on the
original. Effectively this creates a fiber pool.

Ideally, the .alternate field shouldn't be used outside of clone
so that everything can work with pure immutability. I cheat a bit
for now so I don't have to pass both trees everywhere.

ReactChildFiber is a bit hacky for reuse and doesn't solve all
cases. Will fix that once I try to get parity.