[css-images] Replaced <length> | <percentage> by <length-percentage> and (#268)

<angle> | <percentage> by <angle-percentage>

Author: SebastianZ

css-images-4/Overview.bs

@@ -822,14 +822,14 @@ Gradient Color-Stops</h3>
 		<dfn>&lt;color-stop-list></dfn> =
 			[ <<linear-color-stop>> , <<linear-color-hint>>? ]# , <<linear-color-stop>>
 		<dfn>&lt;linear-color-stop></dfn> = <<color>> && <<color-stop-length>>
-		<dfn>&lt;linear-color-hint></dfn> = <<length>> | <<percentage>>
-		<dfn>&lt;color-stop-length></dfn> = [ <<length>> | <<percentage>> ]{1,2}
+		<dfn>&lt;linear-color-hint></dfn> = <<length-percentage>>
+		<dfn>&lt;color-stop-length></dfn> = <<length-percentage>>{1,2}
 
 		<dfn>&lt;angular-color-stop-list></dfn> =
 			[ <<angular-color-stop>> , <<angular-color-hint>>? ]# , <<angular-color-stop>>
 		<dfn>&lt;angular-color-stop></dfn> = <<color>> && <<color-stop-angle>>?
-		<dfn>&lt;angular-color-hint></dfn> = <<angle>> | <<percentage>>
-		<dfn>&lt;color-stop-angle></dfn> = [ <<angle>> | <<percentage>> ]{1,2}
+		<dfn>&lt;angular-color-hint></dfn> = <<angle-percentage>>
+		<dfn>&lt;color-stop-angle></dfn> = <<angle-percentage>>{1,2}
 
 		<dfn>&lt;color-stop></dfn> = <<color-stop-length>> | <<color-stop-angle>>
 	</pre>

css-images/Overview.bs

@@ -763,7 +763,7 @@ Radial Gradients: the ''radial-gradient()'' notation {#radial-gradients}
 			<<size>> may instead be given explicitly as:
 
 			<dl>
-				<dt><dfn for="<size>">[ <<length>> | <<percentage>> ]{2}</dfn>
+				<dt><dfn for="<size>"><<length-percentage>>{2}</dfn>
 				<dd>
 					Gives the size of the ellipse explicitly.
 					The first value represents the horizontal radius,
@@ -780,7 +780,7 @@ Radial Gradients: the ''radial-gradient()'' notation {#radial-gradients}
 		<pre>
 			radial-gradient() = radial-gradient(
 			  [ [ circle               || <<length>> ]                          [ at <<position>> ]? , |
-			    [ ellipse              || [ <<length>> | <<percentage>> ]{2} ]    [ at <<position>> ]? , |
+			    [ ellipse              || <<length-percentage>>{2} ]            [ at <<position>> ]? , |
 			    [ [ circle | ellipse ] || <<extent-keyword>> ]                  [ at <<position>> ]? , |
 			    at <<position>></span> ,
 			  ]?
@@ -1014,7 +1014,7 @@ Gradient Color-Stops {#color-stop-syntax}
 
 	<pre class=prod>
 		<dfn>&lt;color-stop-list></dfn> = <<color-stop>>{2,}
-		<dfn>&lt;color-stop></dfn> = <<color>> [ <<percentage>> | <<length>> ]?
+		<dfn>&lt;color-stop></dfn> = <<color>> <<length-percentage>>?
 	</pre>
 
 	The colors in gradients are specified using <a>color stops</a>.