Scalar addition arrays

```js
var a = [1, 2, 3];
var x = 1 + a;

// x = [2,3,4]
```

```js
var a = ["foo", "bar"];
var x = "foo" + a;

// x = ["foofoo", "foobar"]
```

```js
var a = ["foo", "bar"];
var x = a + "foo";

// x = ["foofoo", "barfoo"]
```