Havocing of frozen objects is broken

[NTillmann]

In the havoc implementation, frozen objects are currently excluded: https://github.com/facebook/prepack/blob/679b7d092e2adcef615004628820c78fa7be728c/src/utils/havoc.js#L172

This is not working as intended, as frozen objects might not be fully rehydrated by the serialized code. The following failing test case illustrates this.

function f(c, g) {
    var o = {};
    o.foo = 42;
    if (c) {
        Object.freeze(o);
        return g(function() { return o.foo; });
    } else {
        o.foo = Date.now();
        Object.freeze(o);
    }
}

Other things to consider:

• When the HavocImplementation sees an object, it might not yet be frozen, but become frozen later.
• There's currently some code to exclude react elements as they supposedly get frozen later. This special case should be removed as well.

[sebmarkbage]

One thing to consider here is that React elements should not be considered frozen objects. They are a different category of objects that are considered “frozenish”. They should never emit Object.freeze calls but we still know that they’re immutable.

I think that’s the source of confusion here.