r193027 - Add isFirstDecl to DecBase too and use it instead of getPreviousDecl() == 0.

[Rafael Espíndola]

On 18 October 2013 23:19, Sean Silva <silvas at purdue.edu> wrote:
> +  /// \brief Returns true if this is the first declaration.
> +  bool isFirstDecl() const {
>
> This comment doesn't add anything. First declaration of what? in what?

It seemed clear given the context. It is the same comment in
Redeclarable.h. Any suggestions?

Cheers,
Rafael