[css-images-3] Attach old IDs.

Author: fantasai

css-images-3/Overview.bs

@@ -1162,12 +1162,12 @@ Object-Sizing Terminology {#sizing-terms}
 	to make it easier to refer to various concepts:
 
 	<dl export>
-		<dt oldids="intrinsic-dimensions,intrinsic-width,intrinsic-height,intrinsic-aspect-ratio"><dfn>natural dimension</dfn>
+		<dt id="intrinsic-dimensions"><dfn id="natural-dimensions" lt="natural dimension">natural dimensions</dfn>
 		<dd>
 			The term [=natural dimensions=] refers to the set of
-			the <dfn>natural height</dfn>,
-			<dfn>natural width</dfn>,
-			and <dfn>natural aspect ratio</dfn>
+			the <dfn oldids="intrinsic-height">natural height</dfn>,
+			<dfn oldids="intrinsic-width">natural width</dfn>,
+			and <dfn oldids="intrinsic-aspect-ratio">natural aspect ratio</dfn>
 			(the ratio between the width and height),
 			each of which may or may not exist for a given [=object=].
 			These natural dimensions represent the preferred sizing intrinsic to the object itself;