Bug 164070 Support widows/orphans properties on text item
Support widows/orphans properties on block text item(label, text, data etc), About the definition of widows/orphans, please refer to CSS spec.
model/org.eclipse.birt.report.model.tests/test/org/eclipse/birt/report/model/api/DesignElementHandleTest.java
* <tr>
 * <td></td>
 * <td>Gets choices of the Data#DISTINCT_PROP property of a label.</td>
 * <td>It has no choices.</td>
 * </tr>
 * <tr>
 * <td>testExtends</td>
 * <td>Gets the extend element from labels that are in body, master-page and
 * components slots.</td>
 * <td>Returned elements match with definition in the design file.</td>
 * </tr>
 * <tr>
 * <td></td>
 * <td>Sets and clears the extends of an element.</td>
 * <td>The extends is set and cleared correctly.</td>
 * </tr>
 * <tr>
 * <td>testOtherMethods</td>
 * <td>Moves a label from the body slot to components slot.</td>
 * <td>The container is ReportDesign and the slot is components slot.</td>
 * </tr>
 * <tr>
 * <td></td>
 * <td>Tests the number of properties of a label.</td>
 * <td>The number is 52.</td>
 * </tr>
 * <tr>
 * <td></td>
 * <td>Drops a label from the design file.</td>
 * <td>The label cannot be find and it has no container.</td>