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
* 
	 * @return a corresponding FontHandle or <code>null</code>.
	 * 
	 * @see FontHandle
	 */
	protected FontHandle getFontProperty( )
	{
		ElementPropertyDefn propDefn = getElement( ).getPropertyDefn(
				Style.FONT_FAMILY_PROP );
		if ( propDefn == null )
			return null;
		return new FontHandle( this );
	}
	/**
	 * Returns the value of an element reference property. Returns a handle to
	 * the referenced element, or <code>null</code> if the reference is
	 * unresolved or unset.
	 * 
	 * @param propName
	 *            the name of the property.
	 * @return a corresponding DesignElement handle to the referenced element
	 */
	public DesignElementHandle getElementProperty( String propName )
	{
		DesignElement target = getElement( ).getReferenceProperty( module,
				propName );
		if ( target == null )
			return null;
		return target.getHandle( module );
	}