Bug 121498 When datasource/dataset deleted, the datasource/dataset property binding element haven't been deleted
When deleted the datasource/dataset, the datasource/dataset property binding element haven't been deleted. Expected result: This operation must be a transaction.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/DesignElementHandle.java
{
	/**
	 * Provides overall information about the module, especially the command
	 * stack.
	 */
	protected final Module module;
	/**
	 * API slot handle array for all slots of this element.
	 */
	private SlotHandle[] slotHandles = null;
	/**
	 * Constructs a handle with the given module.
	 * 
	 * @param module
	 *            the module
	 */
	public DesignElementHandle( Module module )