Let Node.managed become CSS-styleable

Summary

Node's managed property should be CSS styleable

Problem

A Node can be hidden via CSS by setting "visibility: hidden". However, an invisible Node still occupies space in its Parent. The only way to manage its layout is by setting its width and height to zero using "-fx-pref-width" and "-fx-pref-height" respectively.

Solution

Make managed property of Node class CSS styleable via -fx-managed CSS Property. To implement this managedProperty in Node.java should become a styleable property.

Specification

Update the Node properties in cssref.html:

diff --git a/modules/javafx.graphics/src/main/docs/javafx/scene/doc-files/cssref.html b/modules/javafx.graphics/src/main/docs/javafx/scene/doc-files/cssref.html
index c64dc03cd3..5e33edaed1 100644
--- a/modules/javafx.graphics/src/main/docs/javafx/scene/doc-files/cssref.html
+++ b/modules/javafx.graphics/src/main/docs/javafx/scene/doc-files/cssref.html
@@ -1750,6 +1750,13 @@
           <td>See <a href="http://www.w3.org/TR/CSS2/visufx.html#visibility">W3C
               visibility property</a></td>
         </tr>
+        <tr>
+            <th class="propertyname" scope="row">-fx-managed</th>
+            <td class="value"><a href="#typeboolean" class="typelink"><boolean></a></td>
+            <td class="default">true</td>
+            <td class="range">&nbsp;</td>
+            <td>Defines whether this node's layout will be managed by its parent</td>
+        </tr>
       </tbody>
     </table>
     <h4>Pseudo-classes</h4>