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/core/Module.java
}
	/**
	 * Drops an element from the id-to-element map. Does nothing if IDs are not
	 * enabled. Should be called only from the
	 * {@link org.eclipse.birt.report.model.command.ContentCommand ContentCommand}.
	 * 
	 * @param element
	 *            The old element to remove.
	 */
	public void dropElementID( DesignElement element )
	{
		if ( idMap == null )
			return;
		assert element.getID( ) > 0;
		Long idObj = new Long( element.getID( ) );
		assert idMap.containsKey( idObj );
		idMap.remove( idObj );
	}
	/**
	 * Looks up an element given an element ID. Returns null if no element
	 * exists with the given ID. Also returns null if IDs are not enabled. Note:
	 * this method will not find an element that has previously been deleted
	 * from the module, even if that element still exists in memory in
	 * anticipation of issuing an undo of the delete. That is, only valid
	 * elements can be found.
	 * 
	 * @param id
	 *            The id of the element to find.
	 * @return The element itself, or null if the element can't be found or if
	 *         IDs are not enabled.