Smart constant rewriting

[kangax]

(as suggested by @sebmarkbage)

The minifier already has simple constant folding and/or dead-code elimination of primitives:

if (__DEV__) {
}

It would be great if it could also do that for frozen objects and non-writable/non-configurable properties.

If I declare an object like:

var obj = {};
Object.defineProperty(obj, 'foo', { configurable: false, writable: false, value: false });

Then this expression should also evaluate to false and be dead-code eliminated:

if (obj.foo) {
}

If the primitive value is a number or boolean it would rewrite it:

var x = obj.foo;

could be rewritten to:

var x = 123;

However, the most important one for potential further optimization would be rewriting bindings for non-primitives;

A binding like:

obj.foo();

would be rewritten to:

foo();

and the minifier would somehow communicate back that the obj binding is now replaced with the foo binding which should have the value of obj.foo.