[css-fonts-4] add unicode value to font-variant-emoji, close #1223

Author: svgeesus

css-fonts-4/Overview.bs

@@ -4675,7 +4675,7 @@ Selecting the text presentation style: The 'font-variant-emoji' property</h3>
 
 <pre class="propdef">
 Name: font-variant-emoji
-Value: auto | text | emoji
+Value: auto | text | emoji | unicode
 Initial: auto
 Applies to: all elements
 Inherited: yes
@@ -4741,10 +4741,7 @@ considered when the user-agent decides whether to use emoji presentation or text
 	<dd>
 		User Agents can choose to draw a <a>Presentation Participating Code Point</a>
 		in either emoji style or text style.
-		User Agents may wish to follow
-		the <a href="http://www.unicode.org/reports/tr51/index.html#Presentation_Style">guidance</a> of the Unicode Consortium
-		when performing this decision.
-		User agents also may wish to follow platform conventions when performing this decision.
+		User agents typically follow platform conventions when performing this decision.
 
 
 	<dt><dfn>text</dfn>
@@ -4757,6 +4754,18 @@ considered when the user-agent decides whether to use emoji presentation or text
 	<dd>
 		Code points are rendered as if U+FE0F VARIATION SELECTOR-16
 		 was appended to every <a>Presentation Participating Code Point</a>.
+
+	<dt><dfn>unicode</dfn></dt>
+	<dd>
+		Code points are rendered in accordance with [[!UTR51]]
+		as either emoji-default, text-default, or text-only,
+		depending on the values of the Emoji and Emoji_Presentation
+		properties for each
+		<a>Presentation Participating Code Point</a>.
+		If present, FE0E VARIATION SELECTOR-15 and U+FE0F VARIATION SELECTOR-16
+		will override the default presentation of individual
+		<a>Presentation Participating Code Points</a>.
+	</dd>
 </dl>
 
 <div class="example">