[cssom-view-1] Fix a logic error and unparseable sentence in the Terminology section.

Author: smfr

cssom-view-1/Overview.bs

@@ -124,8 +124,8 @@ HTML.
 <dfn>Content edge</dfn>, <dfn>padding edge</dfn>, <dfn>border edge</dfn>, <dfn>margin edge</dfn>, and <dfn>viewport</dfn> are defined by CSS.
 <!-- These *should* just link to CSS2.1, but it doesn't have actual anchors to link to, because it's THE WORST. -->
 
-Elements and <a>viewports</a> have an associated <dfn export>scrolling box</dfn> if the element or viewport 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]]
+Elements and <a>viewports</a> have an associated <dfn export>scrolling box</dfn> if the element or viewport 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 not ''overflow/hidden'' or ''overflow/clip''. [[!CSS3-BOX]]
 
 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:
@@ -1761,6 +1761,7 @@ generally not listed.
 
 <h3 id='changes-from-2020-10-19' class=no-num>Changes From 19 October 2020</h3>
 * Added the "Security and Privacy Considerations" section
+* Fixed a logical error in the Terminology section.
 
 <h3 id='changes-from-2020-01-31' class=no-num>Changes From 31 January 2020</h3>
 * Added Simon Fraser as editor