Align Flexbox's treatment of align-self on abspos elements with Alignment's. This is a minor behavior change for some abspos elements.

Author: tabatkins

css-flexbox/Overview.bs

@@ -656,6 +656,8 @@ Absolutely-Positioned Flex Children</h3>
 	as if it were the sole <a>flex item</a> in the <a>flex container</a>,
 	assuming both the child and the flex container
 	were fixed-size boxes of their used size.
+	For this purpose,
+	a value of ''align-self: auto'' is treated identically to ''align-self/start''.
 
 	<div class='example'>
 		The effect of this is that if you set, for example,
@@ -1958,7 +1960,9 @@ Cross-axis Alignment: the 'align-items' and 'align-self' properties</h3>
 	If either of the <a>flex item's</a> cross-axis margins are <a value for=margin>auto</a>,
 	'align-self' has no effect.
 
-	A value of <dfn value for=align-self>auto</dfn> for 'align-self'
+	On <a>absolutely positioned</a> elements,
+	a value of ''align-self/auto'' computes to itself.
+	On all other elements, a value of <dfn value for=align-self>auto</dfn> for 'align-self'
 	computes to the value of 'align-items' on the element’s parent,
 	or ''align-self/stretch'' if the element has no parent.
 	The alignments are defined as: