[css-grid-3][masonry] item-tolerance: normal is used-value default #12111

Since it needs to vary between masonry (1em) and flexbox (0).
See #3071

Author: fantasai

css-grid-3/Overview.bs

@@ -791,13 +791,9 @@ Placement Precision: the 'item-tolerance' property</h3>
 			that is probably appropriate to represent “close enough”.
 
 		: <dfn>normal</dfn>
-		:: Resolves to a value of ''1em''.
+		:: Resolves to a [=used value=] of ''1em'' in [=masonry layout=]
+			and a [=used value=] of ''0'' in all other layout modes.
 			<!-- This default is consistent with gaps. -->
-			ISSUE(12111): Should this be a [=used value=] or [=computed value=] of ''1em''?
-			Used values would allow easier responsiveness to different layout modes,
-			and would be more consistent with 'gap',
-			but computed values would enable interpolation with <<length-percentage>> values
-			and are simpler to manage otherwise.
 
 		: <dfn>infinite</dfn>
 		:: Specifies an infinite [=tie threshold=].
@@ -817,6 +813,10 @@ Placement Precision: the 'item-tolerance' property</h3>
 
 	ISSUE(10884): The CSSWG is open to better names for this property.
 
+	Note: We expect to apply this property to [=flex layout=] in the future also,
+	see <a href='https://github.com/w3c/csswg-drafts/issues/3071'>discussions</a>
+	on how that might work.
+
 <h3 id="masonry-layout-algorithm">
 Masonry Layout and Placement Algorithm</h3>