[ttml2] Add background related styles

skynavga has just created a new issue for 
https://github.com/w3c/ttml2:

== Add background related styles ==
Need to add the following styles based on CSS Backgrounds and Borders 
Level 3:

* tts:backgroundClip
* tts:backgroundOrigin
* tts:backgroundSize

These styles are desirable to adequately support background images on 
regions and content elements.

Please view or discuss this issue at 
https://github.com/w3c/ttml2/issues/175 using your GitHub account

Received on Thursday, 8 September 2016 23:24:47 UTC