UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_9_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/48.0.2564.116 Safari/537.36

Example URL:

Steps to reproduce the problem:
1. Open the attached test case and the inspector.
2. Reload the attached test case a couple times and observe the console output.

Every now and then you should see "FontFace was in document but can't not be loaded". Most of the time it shows up once, but I've seen it happen more than that.

What is the expected behavior?
The expected behaviour is that "document.fonts.load" immediately recognises the new FontFace rule and does not resolves the promise with an empty font face list (indicating there is no matching font, even though there should be). 

Other CSS rules are correctly recognised and applied as soon as the stylesheet's "onload" handler is called.

What went wrong?
Calling "document.fonts.load" in the "onload" handler of a stylesheet containing font face rules sometimes results in an empty font face list. By the time the "onload" handler is called, the CSSOM for that stylesheet should have been constructed and any font face rules in it should be recognised by the font matching algorithm.

This behaviour does not happen in Firefox.

Does it occur on multiple sites: Yes

Is it a problem with a plugin? No 

Did this work before? No 

Does this work in other browsers? Yes 

Chrome version: 48.0.2564.116  Channel: n/a
OS Version: OS X 10.9.3
Flash Version: Shockwave Flash 20.0 r0

This problem makes it hard to reliably use the css font loading API, because it incorrectly results in an empty font face list even though the stylesheet contains web fonts.

I had to work around this issue in the Web Font Loader (https://github.com/typekit/webfontloader/blob/master/src/core/nativefontwatchrunner.js#L39) by repeatedly calling document.fonts.load until a font is recognised and loaded (instead of calling it once, after receiving the "load" event from a stylesheet containing fonts).
 

Deleted: fonts.zip 6.7 KB

fonts.zip 6.7 KB Download