[css-overflow-5] Limit scrolling when activating a marker (#11674)

When activating a marker, as resolved in #11138 scrolling should be limited to the scrolling containers associated with the marker targets.
This builds on the addition of container to the scroll into view algorithm in #11673.

Author: flackr

css-overflow-5/Overview.bs

@@ -398,7 +398,8 @@ Selecting The Active Scroll Marker: the '':target-current'' pseudo-class</h4>
 		1. Let <var>element</var> be the [=scroll target=] of the control.
 		1. Let <var>block</var> be "<code>start</code>".
 		1. Let <var>inline</var> be "<code>start</code>".
-		1. <a lt='scroll a target into view'>Scroll the |element| into view</a> with <var>block</var> and <var>inline</var>.
+		1. Let <var>container</var> be the nearest common ancestor <a>scroll container</a> of the scroll markers in the [=scroll marker group=] associated with this [=scroll marker=].
+		1. <a lt='scroll a target into view'>Scroll the |element| into view</a> with <var>block</var>, <var>inline</var>, and <var>container</var>.
 		1. 	: If the activation was triggered by invocation
 			::
 				1. <a spec=html>Follow the hyperlink</a> updating the URL, however retain focus on the marker element.