[css-sizing-4] contain-intrinsic-* properties should not allow negative lengths. See #11945 (#11959)

Author: weinig

css-sizing-4/Overview.bs

@@ -530,7 +530,7 @@ Overriding Contained Intrinsic Sizes: the 'contain-intrinsic-*' properties</h3>
 
 	<pre class=propdef>
 	Name: contain-intrinsic-width, contain-intrinsic-height, contain-intrinsic-block-size, contain-intrinsic-inline-size
-	Value: auto? [ none | <<length>> ]
+	Value: auto? [ none | <<length [0,∞]>> ]
 	Initial: none
 	Inherited: no
 	Logical property group: contain-intrinsic-size