Gravity Forms has since added their own icon that better fits the WordPress admin UI, rendering this unnecessary.
If you’re someone like me that spends a lot of time in the WordPress admin, you’ll realize that little details in the UI can make a big difference. Combine that with my already slightly OCD bent, and it probably won’t surprise anyone that I find the lack of a Dashicon for Gravity Forms extremely annoying… so much so that I decided to make a plugin to fix it.
You can download it on GitHub. Hopefully they’ll update the core plugin before too long and this can become unnecessary.