[css-pseudo-4] Add white-space to ::marker per #4448 (comment)

Author: fantasai

css-pseudo-4/Overview.bs

@@ -737,6 +737,7 @@ List Markers: the ''::marker'' pseudo-element</h3>
   The following CSS properties apply to a ''::marker'' pseudo-element:
   <ul>
     <li>all font properties (see [[CSS3-FONTS]])
+    <li>the 'white-space' property (see [[CSS3TEXT]])
     <li>the 'color' property (see [[CSS3COLOR]])
     <li>the 'text-combine-upright', 'unicode-bidi', and 'direction' properties (see [[CSS-WRITING-MODES-3]])
     <li>the 'content' property (see [[CSS-LISTS-3]])