Fix empty @since

Change-Id: Ie060beaa9eca3b098d7e07116d64580c6a198ee8

client/src/com/vaadin/client/connectors/GridConnector.java

     /**
      * Class for handling scrolling issues with open details.
      * 
-     * @since
-     * @author Vaadin Ltd
+     * @since 7.5.2
      */
     private class LazyDetailsScroller implements DeferredWorker {
 
         /**
          * Inform LazyDetailsScroller that a details row has opened on a row.
          * 
-         * @since
          * @param rowIndex
          *            index of row with details now open
          */