[css3-flexbox] Clarify that 'align-self:stretch' only works on computed-time ''auto'', not things like a percentage that causes auto behavior at used-value time.

Author: tabatkins

css3-flexbox/Overview.html

@@ -3270,7 +3270,7 @@ <h3 id=cross-sizing><span class=secno>9.4. </span> Cross size determination</h3>
 
    <li id=algo-stretch> <strong>Determine the used cross size of each flex
     item.</strong> If a flex item has ‘<code class=css>align-self:
-    stretch</code>’, its cross size property is ‘<code
+    stretch</code>’, its computed cross size property is ‘<code
     class=css>auto</code>’, and neither of its cross-axis margins are
     ‘<code class=css>auto</code>’, the used outer cross size is the used
     cross size of its flex line, clamped according to the item's min and max
@@ -3965,6 +3965,11 @@ <h2 class=no-num id=changes>Changes</h2>
    <li> Correct an omission in the flex-line size determination, so a
     single-line flexbox will size to its contents if it doesn't have a
     definite size.
+
+   <li> Clarify that ‘<a href="#align-content-stretch"><code
+    class=property>stretch</code></a>’ checks for the <em>computed</em>
+    value of the cross-size property, which means that percentages that can't
+    be resolved at computed-value time aren't stretched.
   </ul>
 
   <p>A <a

css3-flexbox/Overview.src.html

@@ -2557,7 +2557,7 @@ <h3 id='cross-sizing'>
 		<li id='algo-stretch'>
 			<strong>Determine the used cross size of each flex item.</strong>
 			If a flex item has ''align-self: stretch'',
-			its cross size property is ''auto'',
+			its computed cross size property is ''auto'',
 			and neither of its cross-axis margins are ''auto'',
 			the used outer cross size is the used cross size of its flex line,
 			clamped according to the item's min and max cross size properties.
@@ -3265,6 +3265,9 @@ <h2 class="no-num" id="changes">Changes</h2>
 
 		<li>
 			Correct an omission in the flex-line size determination, so a single-line flexbox will size to its contents if it doesn't have a definite size.
+
+		<li>
+			Clarify that 'stretch' checks for the <em>computed</em> value of the cross-size property, which means that percentages that can't be resolved at computed-value time  aren't stretched.
 	</ul>
 
 	<p>A <a href="http://dev.w3.org/csswg/css3-flexbox/issues-lc-2012">Disposition of Last Call Comments</a> is available.