[css-display-3] Add some notes about the SVG attributes rule from the issue discussion. #2502

Author: fantasai

css-display-3/Overview.bs

@@ -1274,6 +1274,21 @@ SVG Elements {#unbox-svg}
 	thus such attributes can affect
 	the layout and visual formatting of the element’s descendants
 	by influencing the values of such properties on those descendants.
+	<!--
+		https://github.com/w3c/csswg-drafts/issues/2502#issuecomment-378809174
+		The rule here should be,
+		if this attribute were mapped to a CSS property,
+		would it inherit or no?
+		If it wouldn't inherit, then it goes away with display: contents.
+		If it would inherit, then it behaves as if it did.
+		(Because there's been an ongoing trend of converting SVG attributes to CSS properties,
+		we wouldn't want to have any difference in behavior as that process continued.)
+
+		Note that some CSS properties that affect descendant content aren't inherited
+		because we needed to know exactly at which point in the tree they were applied
+		and/or because their effects accumulate.
+		The same is likely to be true of some SVG attributes.
+	-->
 
 MathML Elements {#unbox-mathml}
 -------------------------------