Animation triggers can now be set via template bindings `[]`
BREAKING CHANGE:
animation trigger expressions within the template that are assigned as
an element attribute (e.g. `@prop`) are deprecated. Please use the
Angular2 property binding syntax (e.g. `[@prop]`) when assigning
properties.
```ts
// this is now deprecated
<div @trigger="expression"></div>
// do this instead
<div [@trigger]="expression"></div>
```
It is now possible to set a fallback state that will apply its
styling when the destination state is not detected.
```ts
state("*", style({ ... }))
```
Closes#9013
