[selectors-4] Update summary table with :empty/:blank updates. Fixes w3c#3197

Author: fantasai

selectors-4/Overview.bs

@@ -384,6 +384,11 @@ Selectors Overview</h2>
 				<td>a user-input element E that requires/does not require input
 				<td>[[#opt-pseudos]]
 				<td>3-UI/4
+			<tr>
+				<td><code>E:blank</code>
+				<td>a user-input element E whose value is blank (empty/missing)
+				<td>[[#blank]]
+				<td>4
 			<tr>
 				<td><code>E:user-invalid</code>
 				<td>a user-altered user-input element E with incorrect input (invalid, out-of-range, omitted-but-required)
@@ -397,14 +402,9 @@ Selectors Overview</h2>
 				<td>3
 			<tr>
 				<td><code>E:empty</code>
-				<td>an E element that has no children (neither elements nor text)
+				<td>an E element that has no children (neither elements nor text) except perhaps white space
 				<td>[[#structural-pseudos]]
 				<td>3
-			<tr>
-				<td><code>E:blank</code>
-				<td>an E element that has no content except maybe white space
-				<td>[[#structural-pseudos]]
-				<td>4
 			<tr>
 				<td><code>E:nth-child(<var>n</var> [of <var>S</var>]?)</code>
 				<td>an E element, the <var>n</var>-th child of its parent matching <var>S</var>