That file seems to be part of another plugin, "mojo-marketplace-wp-plugin", added by your hosting provider, BlueHost, when you created your site. It allows the BlueHost WordPress installer to install other plugins, like Jetpack in this case.
The ie-shims.js
is not malicious though, and the "ZXZhbC" text mentioned by WordFence is part of the original file:
https://github.com/Automattic/jetpack-start/blob/master/js/ie-shims.js#L1937
However, I'll see if we can solve that false positive alert generated by WordFence. I'll let you know as soon as I have some news.
In the meantime, you can ignore that warning, the file hasn't been compromised.
Thanks for letting us know!