[css-grid] 'size like a block-level box' is ambiguous; just say 'like a block box'.

Author: tabatkins

css-grid/Overview.bs

@@ -622,7 +622,7 @@ Sizing Grid Containers</h3>
 	A <a>grid container</a> is sized
 	using the rules of the formatting context in which it participates.
 	As a block-level box in a <a>block formatting context</a>,
-	it is sized like any other block-level box that establishes a formatting context,
+	it is sized like a block box that establishes a formatting context,
 	with an ''auto'' inline size calculated as for in-flow block boxes.
 	As an inline-level box in an inline formatting context,
 	it is sized as an atomic inline-level box (such as an inline-block).