[css-cascade] Moving Writing Modes from a normative to informative ref

While attempting to publish the CR of the Cascade module, Chris Lilley
found that we were normatively referencing Writing Modes, which is
still relatively immature.  (This was brought up during the transition
call.)  It was only referenced in a Note block, so I've just adjusted
the reference to be non-normative instead.

~TJ

Received on Monday, 30 September 2013 22:41:42 UTC