[css-grid-1] Add IDs for intrinsic track algo steps.

Author: fantasai

css-grid-1/Overview.bs

@@ -3703,7 +3703,7 @@ Resolve Intrinsic Track Sizes</h3>
 -->
 
 	<ol>
-		<li>
+		<li id="algo-baseline-shims">
 			<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>,
@@ -3739,7 +3739,7 @@ Resolve Intrinsic Track Sizes</h3>
 			<a href="#row-align">do not participate in baseline alignment</a>,
 			they are not shimmed.
 
-		<li>
+		<li id="algo-single-span-items">
 			<strong>Size tracks to fit non-spanning items:</strong>
 			For each track with an intrinsic <a>track sizing function</a>,
 			consider the items in it with a span of 1:
@@ -3798,7 +3798,7 @@ Resolve Intrinsic Track Sizes</h3>
 			In all cases, if a track’s <a>growth limit</a> is now less than its <a>base size</a>,
 			increase the <a>growth limit</a> to match the <a>base size</a>.
 
-		<li>
+		<li id="algo-spanning-items">
 			<strong>Increase sizes to accommodate spanning items:</strong>
 			Next, consider the items with a span of 2
 			that do not span a track with a <a>flexible sizing function</a>,
@@ -3891,7 +3891,7 @@ Resolve Intrinsic Track Sizes</h3>
 
 			Repeat incrementally for items with greater spans until all items have been considered.
 
-		<li>
+		<li id="algo-finite-growth">
 			If any track still has an infinite <a>growth limit</a>
 			(because, for example, it had no items placed in it),
 			set its <a>growth limit</a> to its <a>base size</a>.