[css-align] Switch more values to 'behaves as', and use consistent language.

Author: tabatkins

css-align/Overview.bs

@@ -227,24 +227,24 @@ Positional Alignment: the ''center'', ''start'', ''end'', ''self-start'', ''self
 			Aligns the <a>alignment subject</a> to be flush with the edge of the <a>alignment container</a>
 			corresponding to the <a>flex container</a>’s main-start or cross-start side, as appropriate.
 			When used on boxes that are not children of a <a>flex container</a>,
-			this value computes to ''start''.
+			this value behaves as ''start''.
 
 		<dt><dfn for="<self-position>, <content-position>">flex-end</dfn> <small>(self, content)</small>
 		<dd><strong>Only used in flex layout.</strong>
 			Aligns the <a>alignment subject</a> to be flush with the edge of the <a>alignment container</a>
 			corresponding to the <a>flex container</a>’s main-end or cross-end side, as appropriate.
 			When used on boxes that are not children of a <a>flex container</a>,
-			this value computes to ''end''.
+			this value behaves as ''end''.
 
 		<dt><dfn for="<self-position>, <content-position>">left</dfn> <small>(self, content)</small>
 		<dd>Aligns the <a>alignment subject</a> to be flush with the <a>alignment container</a>’s <a href="http://www.w3.org/TR/css3-writing-modes/#line-left">line-left</a> edge.
 			If the property's axis is not parallel with the inline axis,
-			this value computes to ''start''.
+			this value behaves as ''start''.
 
 		<dt><dfn for="<self-position>, <content-position>">right</dfn> <small>(self, content)</small>
 		<dd>Aligns the <a>alignment subject</a> to be flush with the <a>alignment container</a>’s <a href="http://www.w3.org/TR/css3-writing-modes/#line-right">line-right</a> edge.
 			If the property's axis is not parallel with the inline axis,
-			this value computes to ''start''.
+			this value behaves as ''start''.
 	</dl>
 
 	<p class='issue'>
@@ -844,8 +844,8 @@ Block/Cross-Axis Alignment: the 'align-self' property</h3>
 			are ignored in favor of alignment as specified here
 			and the used value of the offset properties are not adjusted to correct for the over-constraint.
 
-			The ''align-self/auto'' keyword is equivalent to ''start'' on replaced absolutely-positioned boxes,
-			and equivalent to ''align-self/stretch'' on all other absolutely-positioned boxes.
+			The ''align-self/auto'' keyword behaves as ''start'' on replaced absolutely-positioned boxes,
+			and behaves as ''align-self/stretch'' on all other absolutely-positioned boxes.
 			(This is because CSS 2.1 does not stretch replaced elements to fit into fixed offsets.)
 
 		<dt>Table Cells: