Allow anchor nodes to be any non-atomic inline box

Author: chrishtr

css-scroll-anchoring-1/Overview.bs

@@ -81,7 +81,7 @@ and close to the block start edge of its <a>optimal viewing region</a>.
 Note: If the user agent does not support the 'scroll-padding' property,
 the optimal viewing region of the scrolling box is equivalent to its <a>content area</a>.
 
-The anchor node is either a non-anonymous <a>block box</a> or a <a>text node</a>.
+An anchor node can be any non-<a>atomic inline</a> <a>box</a>.
 The anchor node is always a <a>descendant</a> of the <a>scrolling box</a>.
 In some cases, a scrolling box may not select any anchor node.
 
@@ -157,8 +157,7 @@ the implementation may wait until the anchor node is needed before computing it.
 
 <div algorithm>
 	The <dfn>scroll anchoring bounding rect</dfn> of a DOM node |N|
-	is |N|’s <a>scrollable overflow rectangle</a> if |N| is a <a>block box</a>,
-	or the bounding rect of its <a>line boxes</a> if |N| is a text node.
+	is |N|’s <a>scrollable overflow rectangle</a>.
 </div>
 
 <h3 id="scroll-adjustment">