Skip fonts with a data: URL source from fontPreloading check

[westonruter]

Fixes #1185

[sebastianbenz]

Can you please add a test here: https://github.com/ampproject/amp-toolbox/tree/main/packages/page-experience/test-data/checks/fontPreloading

You can then run npm run test:snapshot to generate a snapshot.

[westonruter]

I added a test in e9159fb.

You can then run npm run test:snapshot to generate a snapshot.

Actually npm run test:optimizer:snapshot, right? In any case, it's not seeming to work for me. Even on main it's failing with a with a bunch of errors like:

I did do npm install. I'm on Node v14.16.0 (LTS).

[sebastianbenz]

You need to run it inside the page-experience directory. Sorry for not mentioning that.

[westonruter]

OK, I'm now in packages/page-experience and I ran npm install. However:

$ npm run test:snapshot

> @ampproject/toolbox-page-experience@2.8.0-canary.14 test:snapshot …/amp-toolbox/packages/page-experience
> PAGE_EXPERIENCE_SNAPSHOT=true jest

sh: jest: command not found

Shouldn't jest be added as a dependency?