[css-overfow] permissive position of text-overflow: ellipsis

Closes #10418

Author: frivoal

css-overflow-4/Overview.bs

@@ -422,6 +422,13 @@ Inline Overflow Ellipsis: the 'text-overflow' property</h3>
 	at the applicable edge(s) of the line as necessary to fit the ellipsis/string, and
 	place the ellipsis/string immediately adjacent
 	to the applicable edge(s) of the remaining inline content.
+
+	In order to avoid jitter in the position of the ellipsis
+	as scrolling reveals more content,
+	user agents may adjust the position of the ellipsis
+	to be adjacent to the end of the line,
+	or may fade/hide the ellipsis during scrolling.
+
 	The first character or
 	<a href="https://www.w3.org/TR/CSS2/visuren.html#inline-boxes">
 	atomic inline-level element</a>