make sure that Function parameters are passed in when using markup

When using markup, you can put some JavaScript in the attribute corresponding to a property of type function. Something like the following:

```html
<my-tag funcAttr="console.log('hello')"></my-tag>
```

and the function will correctly be called.

However imagine that your function has the following signature:

```js
dcl(Widget, {
   functAttr: function(param) {
   }
});
```

You don't get access to "param", meaning you can't do:

```html
<my-tag funcAttr="console.log(attr)"></my-tag>
```

This is particularly annoying for event where for example you would like to be able to do something like the following:


```html
<d-list onselection-change="myviewstack.show(event.newValue"></d-list>
```

This PR is making sure the Function is built with the right parameters so you can do that.