[css-flexbox] Per dholbert's email, we should use 'inner' here, as it represents the amount of shrinkability better.

--HG--
extra : rebase_source : 91c19f2509f4813ffd4de5194922a5c7c34ccb16

Author: tabatkins

css-flexbox/Overview.bs

@@ -2656,7 +2656,7 @@ Resolving Flexible Lengths</h3>
 						<dt>If using the <i>flex shrink factor</i>
 						<dd>
 							For every unfrozen item on the line,
-							multiply its flex shrink factor by its outer flex base size,
+							multiply its flex shrink factor by its inner flex base size,
 							and note this as its <dfn>scaled flex shrink factor</dfn>.
 							Find the ratio of the item's <a>scaled flex shrink factor</a>
 							to the sum of the <a>scaled flex shrink factors</a> of all unfrozen items on the line.