[css-grid] Per WG resolution, accept the 'add shims to maintain baseline-alignment during sizing calculations' solution. Fixes #1039.

Author: tabatkins

css-grid-1/Overview.bs

@@ -3691,8 +3691,6 @@ Resolve Intrinsic Track Sizes</h3>
 
 	<ol>
 		<li>
-			<ins>
-
 			<strong>Shim baseline-aligned items
 			so their intrinsic size contributions reflect their baseline alignment.</strong>
 			For the items in each <a>baseline-sharing group</a>,
@@ -3716,8 +3714,6 @@ Resolve Intrinsic Track Sizes</h3>
 			but they live in separate <a>baseline-sharing groups</a>.
 			[[CSS-ALIGN-3]]
 
-			</ins>
-
 		<li>
 			<strong>Size tracks to fit non-spanning items:</strong>
 			For each track with an intrinsic <a>track sizing function</a>,