[css-inline-3] Remove issue. w3c#5177

Author: fantasai

css-inline-3/Overview.bs

@@ -395,9 +395,6 @@ Baseline Types and Metrics</h3>
 			Corresponds to the ideographic central baseline,
 			halfway between the [=ideographic-under=] and [=ideographic-over=] baselines.
 
-			ISSUE(5177): This is the default baseline in [=vertical writing modes=].
-			Can we make it interoperable? Or do we need another value that is?
-
 		<dt><dfn lt="ideographic-ink-over baseline" local-lt="ideographic-ink-over">ideographic-ink-over</dfn>
 		<dd>
 			Corresponds to the [=line-over=] ink edge of CJK (Han/Hangul/Kana) text.