[css-viewport] [cssom-view-1] Add a definition of the zoom CSS property

cssom-view-1/Overview.bs

@@ -1141,7 +1141,7 @@ aborting on the first step that returns a value:
     1. Return the {{DOMRect}} object in <var>list</var> at index 0.
 1. If <a>caret node</a> is a text entry widget that is a replaced element,
     and that is in the document,
-    return n [=scaled=] {{DOMRect}} object for the caret in the widget
+    return a [=scaled=] {{DOMRect}} object for the caret in the widget
     as represented by the <a>caret offset</a> value.
     The <a>transforms</a> that apply to the element and its ancestors are applied.
 1. Return null.