How to handle declarations with unused definitions

Given a JS program like
```
var x = 9;
x = 10;
console.log(x); // slicing criterion
```

Should the unnecessary define in line 1 be included?
```
var x = 9;
x = 10;
console.log(x); // slicing criterion
```

or instead removed?
```
var x;
x = 10;
console.log(x); // slicing criterion
```
