If this is going to be useful to Typekit, then we'll need to be case-insensitive about the names. Typekit font names are always lower-case, and if it's a font with spaces in the name we'll typically use dashes as well. Additionally, we sometimes load these fonts using entirely different CSS names (like their Typekit opaque ID). Using the fixed names happens to work well with Google's service, but doesn't work as well with Typekit (or potentially other services) because there's no guarantee there that a given font will be mapped to a given name.

I'm not sure if this is harmful, but it's definitely still Google specific. Could/should we keep this as a configurable option just to pass in optional metrics-compatible fonts, and let the Google module pass in their list somehow?