Eliminate if statements when condition is provably true/false

Assume the following code:

```
function foo() {
if (bar() || true) {
baz();
} else {
NOT_REACHABLE();
}
}
```

Currently, babel-minify transforms this to:

```
function foo(){bar()||!0?baz():NOT_REACHABLE()}foo();
```

UglifyJS3 transforms to:

```
function foo(){bar(),baz()}foo();
```

It would be nice if babel-minify could eliminate the `if` statement entirely.