duplicate overflow values

Author: estelle

modules/overflow.html

@@ -39,43 +39,43 @@
       }
 
       .hidden {
-        overflow: hidden;
+        overflow: hidden hidden;
       }
       .hidden::before {
         content: "hidden: ";
       }
 
       .clip {
-        overflow: clip;
+        overflow: clip clip;
       }
       .clip::before {
         content: "clip: ";
       }
 
       .scroll {
-        overflow: scroll;
+        overflow: scroll scroll;
       }
       .scroll::before {
         content: "scroll: ";
       }
 
       .auto {
-        overflow: auto;
+        overflow: auto auto;
       }
       .auto::before {
         content: "auto: ";
       }
 
       .overlay {
-        overflow: clip;
-        overflow: overlay;
+        overflow: clip clip;
+        overflow: overlay overlay;
       }
       .overlay::before {
         content: "overlay (or clip if not supported): ";
       }
 
       .visible {
-        overflow: visible;
+        overflow: visible visible;
       }
       .visible::before {
         content: "visible: ";