[css-grid-1] Treat min-content constraints as zero free space for the…

… purpose of expanding flexible tracks. #3683

css-grid-1/Overview.bs

@@ -4299,18 +4299,19 @@ Expand Flexible Tracks</h3>
 	First, find the used <a>flex fraction</a>:
 
 	<dl>
-		<dt>If the <a>free space</a> is zero:
+		<dt>If the <a>free space</a> is zero
+			or if sizing the <a>grid container</a> under a <a>min-content constraint</a>:
 		<dd>
 			The used <a>flex fraction</a> is zero.
 
-		<dt>If the <a>free space</a> is a <a>definite</a> length:
+		<dt>Otherwise, if the <a>free space</a> is a <a>definite</a> length:
 		<dd>
 			The used <a>flex fraction</a> is the result of
 			<a href="#algo-find-fr-size">finding the size of an fr</a>
 			using all of the <a>grid tracks</a>
 			and a <a>space to fill</a> of the <a>available grid space</a>.
 
-		<dt>If the <a>free space</a> is an <a>indefinite</a> length:
+		<dt>Otherwise, if the <a>free space</a> is an <a>indefinite</a> length:
 		<dd>
 			The used <a>flex fraction</a> is the maximum of:
 
@@ -4701,6 +4702,19 @@ Major Changes</h4>
 				<ins>or it is a <a>flexible track</a></ins>),
 				set its <a>growth limit</a> to its <a>base size</a>.
 			</blockquote>
+
+		<li id="change-2017-min-content-flex">
+			Treat min-content constraints the same as zero free space
+			when expanding flexible tracks.
+			(<a href="https://github.com/w3c/csswg-drafts/issues/3683">Issue 3683</a>)
+			<blockquote>
+				<dl>
+					<dt>If the <a>free space</a> is zero
+						<ins>or if sizing the <a>grid container</a> under a <a>min-content constraint</a></ins>:
+					<dd>
+						The used <a>flex fraction</a> is zero.
+				</dl>
+			</blockquote>
 	</ul>
 
 <h4 id="clarify-2017">