[web-animations-1][css-transitions-2] Make CSS transitions that aren't tied to markup target the animations level of the cascade

[birtles]

From @birtles on June 30, 2015 23:58

As raised in issue #62 (see w3c/web-animations#62 (comment) and w3c/web-animations#62 (comment))

Copied from original issue: w3c/web-animations#97