Fix for spread on computed context

Right now:
```js
obj[method](...args);
```
will result in:
```js
"use strict";
var _slice = Array.prototype.slice;
obj[method.apply](_slice.call(args));
```
instead of:
```js
"use strict";
var _slice = Array.prototype.slice;
obj[method].apply(_slice.call(args));
```
This fixes that.