[css-images-3] Merge the two image-orientation:<angle> grammar clauses.

Author: tabatkins

css-images-3/Overview.bs

@@ -1510,7 +1510,7 @@ Image Processing {#image-processing}
 
 	<pre class='propdef'>
 	Name: image-orientation
-	Value: from-image | none | <<angle>> | [ <<angle>>? flip ]
+	Value: from-image | none | [ <<angle>> || flip ]
 	Initial: from-image
 	Applies to: all elements
 	Inherited: yes
@@ -1565,9 +1565,9 @@ Image Processing {#image-processing}
 			If there is no orientation specified in its metadata,
 			this value computes to ''image-orientation/none''.
 
-		<dt><dfn><<angle>></dfn>
+		<dt><dfn lt="<angle>|flip|<angle> || flip"><<angle>> || flip</dfn>
 		<dd>
-			Positive values cause the image to be rotated to the right
+			Positive <<angle>> values cause the image to be rotated to the right
 			(in a clockwise direction),
 			while negative values cause a rotation to the left.
 			The computed value of the property is calculated
@@ -1576,26 +1576,20 @@ Image Processing {#image-processing}
 			then rounding it to the nearest quarter-turn,
 			rounding away from 0
 			(so ''45deg'' rounds to ''90deg'', etc).
+			If the <<angle>> is omitted, it defaults to ''0deg''.
+
+			If ''flip'' is specified,
+			after rotation the image is flipped horizontally.
 
 			This value only applies to content images;
 			decorative images continue to behave as ''from-image''.
 			This value is deprecated
 			and is optional for implementations
 			except those conforming to [[!CSS-PRINT]].
 
-		<dt><dfn><<angle>>? flip</dfn>
-		<dd>
-			Identical to the plain <<angle>> case,
-			except that after rotation the image is flipped horizontally.
-			If the <<angle>> is omitted,
-			it defaults to ''0deg''.
-
-			This value only applies to content images;
-			decorative images continue to behave as ''from-image''.
-			This value is deprecated
-			and is optional for implementations.
-
-			Note: This value is only necessary to represent all 8 possible EXIF orientations that <a value for=image-orientation>from-image</a> can produce.
+			Note: This value allows all 8 possible EXIF orientations
+			that ''image-orientation/from-image'' can produce
+			to be manually reproduced.
 	</dl>
 
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