[css-grid] Rename 'hypothetical flex fraction' to 'hypothetical fr size'. Handle sums of flex factors <1 same as flexbox does.

Author: tabatkins

css-grid/Overview.bs

@@ -3005,24 +3005,25 @@ Find the Size of an ''fr''</h4>
 			minus the <a>base sizes</a> of the non-flexible <a>grid tracks</a>.
 
 		<li>
-			Let the <dfn>hypothetical flex fraction</dfn>
+			Let <dfn>flex factor sum</dfn> be the sum of the <a>flex factors</a> of the flexible tracks.
+			If this value is less than 1,
+			set it to 1 instead.
+
+		<li>
+			Let the <dfn>hypothetical fr size</dfn>
 			be the <a>leftover space</a>
-			divided by the sum of the <a>flex factors</a> of the flexible tracks.
+			divided by the <a>flex factor sum</a>.
 
 		<li>
-			If the product of the <a>hypothetical flex fraction</a> and a flexible track's <a>flex factor</a>
+			If the product of the <a>hypothetical fr size</a> and a flexible track's <a>flex factor</a>
 			is less than the track's base size,
 			restart this algorithm
 			treating all such tracks as inflexible.
 
 		<li>
-			Return the <a>hypothetical flex fraction</a>.
+			Return the <a>hypothetical fr size</a>.
 	</ol>
 
-	<p class='issue'>
-		This section needs adjustment to handle sum(flex-factors) < 1
-		the <a href="http://www.w3.org/TR/css-flexbox-1/#resolve-flexible-lengths">same way Flexbox now does it</a>.
-
 <h2 id='pagination'>
 Fragmenting Grid Layout</h2>