[css-syntax] Need to check for EOF when testing to see if it's a valid escape.

--HG--
extra : rebase_source : 9ce605f0100222ba60f4c09d9b1b742c8f548268

Author: tabatkins

css-syntax/Overview.bs

@@ -1492,7 +1492,7 @@ 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>,
+	if the second <a>code point</a> is a <a>newline</a> or <a>EOF code point</a>,
 	return false.
 
 	Otherwise, return true.

css-syntax/Overview.html

@@ -2591,7 +2591,7 @@ <h4 class="heading settled heading" data-level=4.3.9 id=starts-with-a-valid-esca
 	return false.</p>
 
 <p>Otherwise,
-	if the second <a data-link-type=dfn href=#code-point title="code point">code point</a> is a <a data-link-type=dfn href=#newline title=newline>newline</a>,
+	if the second <a data-link-type=dfn href=#code-point title="code point">code point</a> is a <a data-link-type=dfn href=#newline title=newline>newline</a> or <a data-link-type=dfn href=#eof-code-point title="eof code point">EOF code point</a>,
 	return false.</p>
 
 <p>Otherwise, return true.</p>