Add missing @since 7.2.4 in javadoc

Change-Id: I48c37a377d6764333b83512dc613798aaf39423c

client/src/com/vaadin/client/ResourceLoader.java

      *            listener to notify when script is loaded
      * @param async
      *            What mode the script.async attribute should be set to
+     * @since 7.2.4
      */
     public void loadScript(final String scriptUrl,
             final ResourceLoadListener resourceLoadListener, boolean async) {
      * execution order for dynamically-added scripts.
      * 
      * @return Browser supports script.async='false'
+     * @since 7.2.4
      */
     public static boolean supportsInOrderScriptExecution() {
         return BrowserInfo.get().isIE()

client/src/com/vaadin/client/Util.java

      *
      * @param event
      * @return return key code
+     * @since 7.2.4
      */
     public static int getKeyCode(KeyEvent<?> event) {
         int keyCode = event.getNativeEvent().getKeyCode();

client/src/com/vaadin/client/VTooltip.java

      * 
      * @param info
      *            with the content of the tooltip
+     * @since 7.2.4
      */
     public void initializeAssistiveTooltips() {
         updatePosition(null, true);