```
Code samples added on or after August 20, 2010 are in the public domain.
No licensing notice is necessary, but if you need one, you can use:
"Any copyright is dedicated to the Public Domain.
http://creativecommons.org/publicdomain/zero/1.0/".
```

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Base64_encoding_and_decoding$revision/423185

Is from 2013.

ASF's license policy covers this in two parts:
http://www.apache.org/legal/resolved.html#category-b
http://www.apache.org/legal/resolved.html#can-works-placed-in-the-public-domain-be-included-in-apache-products

It looks like the file should just have a CC-pd0 license block and not an Apache license block.