8015720: since tag isn't copied while generating JavaFX documentation

Reviewed-by: jjg

langtools/test/com/sun/javadoc/testJavaFX/C.java

@@ -57,6 +57,7 @@ public class C {
      * Defines the direction/speed at which the {@code Timeline} is expected to
      * be played.
      * @defaultValue 11
+     * @since JavaFX 8.0
      */
     private DoubleProperty rate;