2.2.50 [W3C-HTML51] Section 11.3.4.2 Downloading or updating an application cache

C0060: Caching progress is not shown

The specification states:

 ... Downloading or updating an application cache
     ...
     Some of these steps have requirements that only apply if the user agent shows caching 
     progress. Support for this is optional. ...

EdgeHTML Mode

Caching progress is not shown.