Fixes #48. Handle resize when no items were visible.

On resize, only reset index for grid (only required there), and handle case where no item was previously visible.

Author: kevinpschaaf

core-list.html

@@ -382,7 +382,9 @@
      * @method updateSize
      */
     updateSize: function() {
-      this._resetIndex(this._getFirstVisibleIndex());
+      if (this.grid) {
+        this._resetIndex(this._getFirstVisibleIndex() || 0);
+      }
       this.initializeData();
     },