[css-cascade-5] Make sure rules sandwiched within the layer get reverted.

Author: fantasai

css-cascade-5/Overview.bs

@@ -1542,10 +1542,11 @@ Rolling Back Cascade Layers: the ''revert-layer'' keyword</h4>
 	If the <a>cascaded value</a> of a property is the <dfn for=all>''revert-layer''</dfn> keyword,
 	the <a>cascaded value</a> is rolled back to the [=layer=] below,
 	so that the <a>specified value</a> is calculated
-	as if no rules were specified in the current [=cascade layer=]
+	as if no rules were specified in the current [=cascade layer=]--
+	or between its [=normal=] and [=important=] levels in the [=cascade=]--
 	for this property on this element.
 
-	Note: If there are no lower-priority layers
+	Note: If there are no lower-priority declarations
 	in the same [=cascade origin=] as the ''revert-layer'' value,
 	the <a>cascaded value</a> will roll back to the previous origin,
 	just as for the [=revert=] keyword.