Selectmenu: Fix invalid empty options in visual test

Author: jzaefferer

tests/visual/selectmenu/selectmenu.html

@@ -226,7 +226,7 @@ <h2>Empty tests</h2>
 
 		<label for="empty2">Select with one empty option element</label>
 		<select name="empty2" id="empty2">
-			<option value=""></option>
+			<option value="" label="empty"></option>
 		</select>
 
 		<label for="empty3">Select with some empty option elements</label>
@@ -235,10 +235,10 @@ <h2>Empty tests</h2>
 			<option value="2" selected="selected">2</option>
 			<option value="3">3</option>
 			<option value="4">4</option>
-			<option value=""></option>
+			<option value="" label="empty"></option>
 			<option value="6">6</option>
 			<option value="7">7</option>
-			<option value=""></option>
+			<option value="" label="empty"></option>
 			<option value="9">9</option>
 		</select>