Update lib.d.ts with this parameters for event handlers

Expected:

Intellisense from `this`

``` ts
// @filename: lib.d.ts
onclick: (this: this, ev: MouseEvent) => any;
// @filename: test.ts
document.documentElement.onclick = function () {
    this./**/
}
```

Actual:
No intellisense from `this`:

``` ts
onclick: (ev: MouseEvent) => any;
```
