[css-images] Per WG resolution, punt cross-fade() to level 4.

Author: tabatkins

css-images-3/Overview.bs

@@ -157,55 +157,6 @@ Image References: the ''url()'' notation {#url-notation}
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-Combining images: the ''cross-fade()'' notation {#cross-fade-function}
-----------------------------------------------------------------------
-
-	When transitioning between images,
-	CSS requires a way to explicitly refer to the intermediate image
-	that is a combination of the start and end images.
-	This is accomplished with the ''cross-fade()'' function,
-	which indicates the two images to be combined
-	and how far along in the transition the combination is.
-
-	Note: Authors can also use the ''cross-fade()'' function for many simple image manipulations,
-	such as tinting an image with a solid color
-	or highlighting a particular area of the page by combining an image with a radial gradient.
-
-	The syntax for ''cross-fade()'' is defined as:
-
-	<pre class=prod>
-		<dfn caniuse="css-cross-fade">cross-fade()</dfn> = cross-fade( <<cf-mixing-image>> , <<cf-final-image>>? )
-		<dfn>&lt;cf-mixing-image></dfn> = <<percentage>>? && <<image>>
-		<dfn>&lt;cf-final-image></dfn> = <<image>> | <<color>>
-	</pre>
-
-	The function represents an image generated by
-	combining two images.
-
-	The <<percentage>> represents how much of the first image is retained
-	when it is blended with the second image.
-	The <<percentage>> must be between ''0%'' and ''100%'' inclusive;
-	any other value is invalid.
-	If omitted,
-	it defaults to the value ''50%''.
-
-	If the last argument is a <<color>>,
-	it represents a solid-color image with the same intrinsic dimensions as the first image.
-	If omitted,
-	it defaults to the color ''transparent''.
-
-	More precisely,
-	given ''cross-fade(<var>p</var> <var>A</var>, <var>B</var>)'',
-	where <var>A</var> and <var>B</var> are images
-	and <var>p</var> is a percentage between 0% and 100%,
-	the function represents an image
-	with width equal to <code>width<sub>A</sub> &times; <var>p</var> + width<sub>B</sub> &times; (1-<var>p</var>)</code>
-	and height equal to <code>height<sub>A</sub> &times; <var>p</var> + height<sub>B</sub> &times; (1-<var>p</var>)</code>.
-	The contents of the image must be constructed by
-	first scaling <var>A</var> and <var>B</var> to the size of the generated image,
-	then applying <code>dissolve(<var>A</var>,<var>p</var>) plus dissolve(<var>B</var>,1-<var>p</var>)</code>.
-	The "dissolve()" function and "plus" compositing operator are defined in the literature by Porter-Duff. [[PORTERDUFF]]
-
 
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css-images-4/Overview.bs

@@ -376,7 +376,53 @@ Image Fallbacks and Annotations: the ''image()'' notation {#image-notation}
 Combining images: the ''cross-fade()'' notation {#cross-fade-function}
 ----------------------------------------------------------------------
 
-Note: No change from [[css3-images]].
+
+
+	When transitioning between images,
+	CSS requires a way to explicitly refer to the intermediate image
+	that is a combination of the start and end images.
+	This is accomplished with the ''cross-fade()'' function,
+	which indicates the two images to be combined
+	and how far along in the transition the combination is.
+
+	Note: Authors can also use the ''cross-fade()'' function for many simple image manipulations,
+	such as tinting an image with a solid color
+	or highlighting a particular area of the page by combining an image with a radial gradient.
+
+	The syntax for ''cross-fade()'' is defined as:
+
+	<pre class=prod>
+		<dfn caniuse="css-cross-fade">cross-fade()</dfn> = cross-fade( <<cf-mixing-image>> , <<cf-final-image>>? )
+		<dfn>&lt;cf-mixing-image></dfn> = <<percentage>>? && <<image>>
+		<dfn>&lt;cf-final-image></dfn> = <<image>> | <<color>>
+	</pre>
+
+	The function represents an image generated by
+	combining two images.
+
+	The <<percentage>> represents how much of the first image is retained
+	when it is blended with the second image.
+	The <<percentage>> must be between ''0%'' and ''100%'' inclusive;
+	any other value is invalid.
+	If omitted,
+	it defaults to the value ''50%''.
+
+	If the last argument is a <<color>>,
+	it represents a solid-color image with the same intrinsic dimensions as the first image.
+	If omitted,
+	it defaults to the color ''transparent''.
+
+	More precisely,
+	given ''cross-fade(<var>p</var> <var>A</var>, <var>B</var>)'',
+	where <var>A</var> and <var>B</var> are images
+	and <var>p</var> is a percentage between 0% and 100%,
+	the function represents an image
+	with width equal to <code>width<sub>A</sub> &times; <var>p</var> + width<sub>B</sub> &times; (1-<var>p</var>)</code>
+	and height equal to <code>height<sub>A</sub> &times; <var>p</var> + height<sub>B</sub> &times; (1-<var>p</var>)</code>.
+	The contents of the image must be constructed by
+	first scaling <var>A</var> and <var>B</var> to the size of the generated image,
+	then applying <code>dissolve(<var>A</var>,<var>p</var>) plus dissolve(<var>B</var>,1-<var>p</var>)</code>.
+	The "dissolve()" function and "plus" compositing operator are defined in the literature by Porter-Duff. [[PORTERDUFF]]
 
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