[cssom-view-1] Fix a typo in specification of scrollParent (w3c#12724)

Author: mrobinson

cssom-view-1/Overview.bs

@@ -1634,7 +1634,7 @@ The <dfn attribute for=HTMLElement>scrollParent</dfn> attribute must return the
     * The element is <a>the <code>body</code> element</a>.
     * The element's computed value of the 'position' property is ''position/fixed'' and no ancestor establishes a fixed position [=containing block=].
 1. Let <var>ancestor</var> be the [=containing block=] of the element in the <a>flat tree</a> and repeat these substeps:
-    1. If <var>ancestor</var> is the [=initial containing block=], return the {{Document/scrollingElement}} for the element's document if it is not <a>closed-shadow-hidden</a> from the element, otherwise reutrn null.
+    1. If <var>ancestor</var> is the [=initial containing block=], return the {{Document/scrollingElement}} for the element's document if it is not <a>closed-shadow-hidden</a> from the element, otherwise return null.
     1. If <var>ancestor</var> is not <a>closed-shadow-hidden</a> from the element, and is a <a>scroll container</a>, terminate this algorithm and return <var>ancestor</var>.
     1. If the computed value of the 'position' property of <var>ancestor</var> is ''position/fixed'',  and no ancestor establishes a fixed position [=containing block=], terminate this algorithm and return null.
     1. Let <var>ancestor</var> be the [=containing block=] of <var>ancestor</var> in the <a>flat tree</a>.