optimization: don't allow mutating the props object

[wmertens]

Proposal

• right now we always create a new props object even when passing spread props
• it could be an optimization to not do that, but disallow mutation of props
• in v2 that's easy to do because the props are proxied

Any other context or information you want to share:

• There are many workarounds possible so it's not limiting
• It might not make a big difference, we need a benchmark
• it would avoid sorted props edge cases