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
import org.eclipse.birt.report.model.api.command.StyleException;
import org.eclipse.birt.report.model.api.command.TemplateException;
import org.eclipse.birt.report.model.api.command.UserPropertyException;
import org.eclipse.birt.report.model.api.core.IDesignElement;
import org.eclipse.birt.report.model.api.core.IStructure;
import org.eclipse.birt.report.model.api.core.Listener;
import org.eclipse.birt.report.model.api.core.UserPropertyDefn;
import org.eclipse.birt.report.model.api.elements.SemanticError;
import org.eclipse.birt.report.model.api.elements.structures.PropertyBinding;
import org.eclipse.birt.report.model.api.metadata.IChoice;
import org.eclipse.birt.report.model.api.metadata.IElementDefn;
import org.eclipse.birt.report.model.api.metadata.IElementPropertyDefn;
import org.eclipse.birt.report.model.api.metadata.ISlotDefn;
import org.eclipse.birt.report.model.api.metadata.PropertyValueException;
import org.eclipse.birt.report.model.api.util.StringUtil;
import org.eclipse.birt.report.model.command.ContentCommand;
import org.eclipse.birt.report.model.command.ExtendsCommand;
import org.eclipse.birt.report.model.command.NameCommand;
import org.eclipse.birt.report.model.command.PropertyCommand;
import org.eclipse.birt.report.model.command.StyleCommand;
import org.eclipse.birt.report.model.command.TemplateCommand;
import org.eclipse.birt.report.model.command.UserPropertyCommand;
import org.eclipse.birt.report.model.core.CachedMemberRef;
import org.eclipse.birt.report.model.core.DesignElement;
import org.eclipse.birt.report.model.core.MemberRef;
import org.eclipse.birt.report.model.core.Module;
import org.eclipse.birt.report.model.core.Structure;
import org.eclipse.birt.report.model.core.StyleElement;
import org.eclipse.birt.report.model.elements.GroupElement;
import org.eclipse.birt.report.model.elements.Library;