ngClass: Add support for conditional map in an array.

Allows for ng-class expressions, like:
```html
<div ng-class=" [classVar, {'is-active': activeVar }] ">
```
Which allows a directive to apply classes it got via attributes in conjunction with conditional classes.
```js
{
	scope: {
	   classVar: '@myBodyClass'
	}
}
```

**The current situation:**
*(Assuming classVar is set to "panel" and activeVar is true)*

Using a map inside an array sets the class to `"panel [Object object]"`

Using a map like `{classVar: true, 'is-active': activeVar }` would set the class to `"classVar is-active"` instead of the desired `"panel is-active"`