[cssom-view] Editorial: potentially scrollable is just for body elements

Author: zcorpan

cssom-view/Overview.bs

@@ -128,15 +128,15 @@ HTML.
 Elements and <a>viewports</a> have an associated <dfn>scrolling box</dfn> if has a scrolling mechanism<!--XXX xref--> or it overflows
 its content area<!--XXX xref--> and the used value of the 'overflow-x' or 'overflow-y' property is ''overflow/hidden''. [[!CSS3-BOX]]
 
-An element is <dfn>potentially scrollable</dfn> if all of the following conditions are true:
+An element <var>body</var> (which will be <a>the HTML <code>body</code> element</a>) is
+<dfn>potentially scrollable</dfn> if all of the following conditions are true:
 
-* The element has an associated <a>CSS layout box</a>.
-* The element is not <a>the HTML <code>body</code> element</a>, or it is and
-    the root element's computed value of the 'overflow-x' or 'overflow-y' properties is not ''overflow/visible''.
-* The element's computed value of the 'overflow-x' or 'overflow-y' properties is not ''overflow/visible''.
+* <var>body</var> has an associated <a>CSS layout box</a>.
+* <var>body</var>'s <a>parent element</a>'s computed value of the 'overflow-x' or 'overflow-y' properties is not ''overflow/visible''.
+* <var>body</var>'s computed value of the 'overflow-x' or 'overflow-y' properties is not ''overflow/visible''.
 
-Note: An element that is <a>potentially scrollable</a> might not have a <a>scrolling box</a>.
-For instance, it could have 'overflow' set to ''overflow/auto'' but not have its content overflowing its content area.
+Note: A <{body}> element that is <a>potentially scrollable</a> might not have a <a>scrolling box</a>.
+For instance, it could have a used value of 'overflow' being ''overflow/auto'' but not have its content overflowing its content area.
 
 A <a>scrolling box</a> of a <a>viewport</a> or element has two <dfn>overflow directions</dfn>, depending on the <a>viewport’s</a> or
 element's <a>block flow direction</a> and <a>inline base direction</a>, as follows: