[css-grid] Define min/max-content constraint handling of 'auto' for span > 1 by defining equivalency instead of embedding rules, per Mats' suggestion. Fixes #500

Author: fantasai

css-grid/Overview.bs

@@ -3898,7 +3898,11 @@ Resolve Intrinsic Track Sizes</h3>
 		<li>
 			<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>:
+			that do not span a track with a <a>flexible sizing function</a>,
+			treating a <a>min track sizing function</a> of ''auto''
+			as ''min-content''/''max-content''
+			when the grid container is being sized under a
+			<a lt="min-content constraint">min</a>/<a>max-content constraint</a> (respectively):
 			<!-- auto-min contribution <= min-content contribution <= max-content contribution -->
 
 			<ol>
@@ -3911,17 +3915,13 @@ Resolve Intrinsic Track Sizes</h3>
 				<li>
 					<strong>For content-based minimums:</strong>
 					Next continue to increase the <a>base size</a> of tracks with
-					a <a>min track sizing function</a> of ''min-content'' or ''max-content'',
-					and tracks with a <a>min track sizing function</a> of ''auto''
-					if the <a>grid container</a> is being sized under a <a>min-content constraint</a>,
+					a <a>min track sizing function</a> of ''min-content'' or ''max-content''
 					by <a href="#extra-space">distributing extra space</a> as needed
 					to account for these items' <a>min-content contributions</a>.
 				<li>
 					<strong>For max-content minimums:</strong>
 					Third continue to increase the <a>base size</a> of tracks with
-					a <a>min track sizing function</a> of ''max-content'',
-					and tracks with a <a>min track sizing function</a> of ''auto''
-					if the <a>grid container</a> is being sized under a <a>max-content constraint</a>,
+					a <a>min track sizing function</a> of ''max-content''
 					by <a href="#extra-space">distributing extra space</a> as needed
 					to account for these items' <a>max-content contributions</a>.
 				<li>

css-grid/issues-cr-2016.bsi

@@ -34,11 +34,13 @@ Closed:   Accepted
 Resolved: Editorial
 ----
 Issue 5.
-Summary:  Fix labels in algo steps
+Summary:  Define equivalency of 'auto' under constraint & -content sizing
 From:     Mats Palmgren
 Comment:  https://github.com/w3c/csswg-drafts/issues/500#issuecomment-249441400
-Open
-Resolved: Editorial
+Response: https://github.com/w3c/csswg-drafts/issues/500#issuecomment-277070479
+Changes:
+Closed:   Accepted
+Resolved: Bugfix
 ----
 Issue 6.
 Summary:  Overflowing alignment is not visible on top/left

css-grid/issues-cr-2016.html

@@ -66,13 +66,15 @@ <h1>CSS Grid Layout Level 1 Disposition of Comments for 2016-09-29 CR</h1>
 <span>Response: <a href='https://lists.w3.org/Archives/Public/www-style/2017Feb/0023.html'>https://lists.w3.org/Archives/Public/www-style/2017Feb/0023.html</a></span>
 <span class="a">Closed:   Accepted</span>
 <span>Resolved: Editorial</span></pre>
-<pre class='open ' id='issue-5'>
+<pre class=' a' id='issue-5'>
 <span>Issue 5. <a href='#issue-5'>#</a></span>
-<span>Summary:  Fix labels in algo steps</span>
+<span>Summary:  Define equivalency of 'auto' under constraint & -content sizing</span>
 <span>From:     Mats Palmgren</span>
 <span>Comment:  <a href='https://github.com/w3c/csswg-drafts/issues/500#issuecomment-249441400'>https://github.com/w3c/csswg-drafts/issues/500#issuecomment-249441400</a></span>
-<span>Open</span>
-<span>Resolved: Editorial</span></pre>
+<span>Response: <a href='https://github.com/w3c/csswg-drafts/issues/500#issuecomment-277070479'>https://github.com/w3c/csswg-drafts/issues/500#issuecomment-277070479</a></span>
+<span>Changes:</span>
+<span class="a">Closed:   Accepted</span>
+<span>Resolved: Bugfix</span></pre>
 <pre class=' oi' id='issue-6'>
 <span>Issue 6. <a href='#issue-6'>#</a></span>
 <span>Summary:  Overflowing alignment is not visible on top/left</span>