It can easily be assumed that the consumer of this library is also using the as3-signals SWC, therefore there's no need to bake it in. The win would be that it would allow for different versions of as3-signals to be used with this library.
For example, I prefer version 0.8 over 0.9-BETA as the latter introduced some significant interface changes. This library appears only to be using add/remove methods from the as3-signals API, which is consistent across all versions.
It can easily be assumed that the consumer of this library is also using the as3-signals SWC, therefore there's no need to bake it in. The win would be that it would allow for different versions of as3-signals to be used with this library.
For example, I prefer version 0.8 over 0.9-BETA as the latter introduced some significant interface changes. This library appears only to be using add/remove methods from the as3-signals API, which is consistent across all versions.