Use the actual original gif the hq2x pictures were generated from. Fixes w3c#188.

Author: tabatkins

css-images/Overview.bs

@@ -1911,15 +1911,15 @@ Determing How To Scale an Image: the 'image-rendering' property {#the-image-rend
 		For example, given the following small image:
 
 		<figure>
-			<img src="images/pixel-art-small.png">
+			<img src="images/pixel-art-small.gif">
 			<figcaption>A small pixel-art image.
 		</figure>
 
 		Scaling it up 3x might look like the following,
 		depending on the value of 'image-rendering':
 
 		<figure>
-			<img src="images/pixel-art-small.png" width=384>
+			<img src="images/pixel-art-small.gif" width=384>
 			<figcaption>The image scaled with ''image-rendering/auto''</figcaption>
 		</figure>