update elements and fix some bugs

lib/src/iron-list/test/helpers.html

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@@ skipping 54 matching lines @@
 
   function getFirstItemFromList(list) {
     var listRect = list.getBoundingClientRect();
     return document.elementFromPoint(listRect.left + 1, listRect.top + 1);
   }
 
   function getLastItemFromList(list) {
     var listRect = list.getBoundingClientRect();
     return document.elementFromPoint(listRect.left + 1, listRect.top + listRect.height - 1);
   }
+
+  function isFullOfItems(list) {
+    var listRect = list.getBoundingClientRect();
+    var listHeight = listRect.height - 1;
+    var item, y = listRect.top + 1;
+    // IE 10 & 11 doesn't render propertly :(
+    var badPixels = 0;
+    while (y < listHeight) {
+      item = document.elementFromPoint(listRect.left + 1, y);
+      if (item.parentNode && !item.parentNode._templateInstance) {
+        badPixels++;
+      }
+      if (badPixels > 3) {
+        return false;
+      }
+      y += 2;
+    }
+    return true;
+  }
 </script>