[css-overflow-3] text-overflow affects an overflowing block ellipsis

Closes #2882

Author: frivoal

css-overflow-3/Overview.bs

@@ -880,10 +880,12 @@ Indicating Block-Axis Overflow: the 'block-ellipsis' property</h3>
 
 	If the <a>block overflow ellipsis</a>
 	is too long to fit in the line,
-	the result is undefined.
+	its layout is undefined
 	(The UA may, for example, treat the <a>block overflow ellipsis</a> as an unbreakable string,
 	or it may lay out the string across more than one line,
-	replacing content in earlier lines as well.)
+	replacing content in earlier lines as well).
+	However, if any part of the [=block overflow ellipsis=] overflows,
+	its rendering is affected by the 'text-overflow' property.
 
 	Issue(2882): There is a suggestion to actually define the behavior
 	when the ellipsis is too long to fit the line.