[css-syntax] Per WG resolution, escaped EOF just becomes U+FFFD, to match impls. Still ignored in a string. Fixes w3c#3182.

Author: tabatkins

css-syntax-3/Overview.bs

@@ -1277,7 +1277,7 @@ Consume an escaped code point</h4>
 	This section describes how to <dfn>consume an escaped code point</dfn>.
 	It assumes that the U+005C REVERSE SOLIDUS (\) has already been consumed
 	and that the next input code point has already been verified
-	to not be a <a>newline</a> or EOF.
+	to be part of a valid escape.
 	It will return a <a>code point</a>.
 
 	Consume the <a>next input code point</a>.
@@ -1297,6 +1297,11 @@ Consume an escaped code point</h4>
 			return U+FFFD REPLACEMENT CHARACTER (�).
 			Otherwise, return the <a>code point</a> with that value.
 
+		<dt>EOF
+		<dd>
+			This is a <a>parse error</a>.
+			Return U+FFFD REPLACEMENT CHARACTER (�).
+
 		<dt>anything else
 		<dd>
 			Return the <a>current input code point</a>.
@@ -1320,7 +1325,7 @@ Check if two code points are a valid escape</h4>
 	return false.
 
 	Otherwise,
-	if the second <a>code point</a> is a <a>newline</a> or EOF,
+	if the second <a>code point</a> is a <a>newline</a>,
 	return false.
 
 	Otherwise, return true.