Danger zone !

Clearing an array with `array.length = 0` or `array = []` not always produce the expected result:
```javascript
var foo = [1, 2, 3];
var bar = foo;

bar.length = 0;
// what the value of foo ?
```
vs:
```javascript
var foo = [1, 2, 3];
var bar = foo;

bar = [];
// what the value of foo ?
```