There are quite a lot of implications in that statement.
Firstly, how does Google see links? If the bot simply reads the link then google will see it as a link to the OP's site. Or does Google see the link AND action the JS and add both, or just the destination link, to the link graph?
If google wouldn't see that as a link to the OP's site, then how is it showing up as an IBL in the first place i.e. how did the OP identify it as a backlink? If the OP used something other than GWT, then is there a difference between how google track IBLs and how the software the OP actually used tracks IBLs?
It seems that you've either made an unsupported guess there or you know something about how google sees links that I don't, if so would you mind explaining it please?