What steps will reproduce the problem?
(1) Enter 'var x = Object.freeze({a: 1})' in the console
(2) Try to modify it, e.g. `x.a = 2`

What is the expected result?
There should be some visual indication that modifying a frozen object won't do anything.  As a user, I have no idea whether something like `this.props` is not writable.

What happens instead?
No indication that x.a = 2 failed.

Perhaps we could explore some 'icy/frozen icon'?