Visit class super_targs in flow_ast_mapper
Visit class super_targs in flow_ast_mapper

Summary:
I've updated the Flow_ast_mapper to visit the class `super_targs` of a parent class.

I noticed the super_targs were not visited when attempting to map over the `type_paramater_instantiantion`'s of a react component.

Example:

```
class Test extends React.Component<Props, State> {
...
}
```

Reviewed By: pieterv

Differential Revision: D7920020

fbshipit-source-id: c19a568b0d9b3f907bf45cad9191ab47d4839110

samwgoldman/flow,popham/flow,facebook/flow,gabelevi/flow,JonathanUsername/flow,gabelevi/flow,samwgoldman/flow,JonathanUsername/flow,jamesgpearce/flow,claudiopro/flow,popham/flow,facebook/flow,mroch/flow,mroch/flow,samwgoldman/flow,nmote/flow,jamesgpearce/flow,gabelevi/flow,mroch/flow,facebook/flow,popham/flow,AgentME/flow,JonathanUsername/flow,jamesgpearce/flow,popham/flow,samwgoldman/flow,facebook/flow,facebook/flow,popham/flow,facebook/flow,JonathanUsername/flow,JonathanUsername/flow,jamesgpearce/flow,gabelevi/flow,gabelevi/flow,claudiopro/flow,popham/flow,nmote/flow,mroch/flow,claudiopro/flow,mroch/flow,samwgoldman/flow,AgentME/flow,samwgoldman/flow,popham/flow,mroch/flow,jamesgpearce/flow,mroch/flow,jamesgpearce/flow,samwgoldman/flow,nmote/flow,AgentME/flow,nmote/flow,AgentME/flow,gabelevi/flow,nmote/flow,jamesgpearce/flow,nmote/flow,JonathanUsername/flow,JonathanUsername/flow,nmote/flow,AgentME/flow,gabelevi/flow,claudiopro/flow,facebook/flow,claudiopro/flow