Bug 163018 An error extension will lead the report contain chart can't be opened and can not new a report.
Details: An error extension will lead the report contain chart can't open In org.eclipse.birt.report.tests.model has an error extension. When run the birt use workbenck, the report contain chart can't be opened and it can not new a report.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/metadata/ElementDefn.java
buildSlots( );
		buildTriggerDefnSet( );
		isBuilt = true;
	}
	/**
	 * Checks the validation of the defined property visibilities. If the
	 * property with the name is not defined, then the visibility is illegal.
	 * 
	 * @throws MetaDataException
	 *             if the property definition is not found
	 */
	private void checkPropertyVisibilities( ) throws MetaDataException
	{
		if ( this.propVisibilites == null )
			return;
		Iterator propNames = this.propVisibilites.keySet( ).iterator( );
		while ( propNames.hasNext( ) )
		{
			String propName = (String) propNames.next( );
			
			if ( getProperty( propName ) == null )
				throw new MetaDataException(
						new String[]{name, propName},
						MetaDataException.DESIGN_EXCEPTION_VISIBILITY_PROPERTY_NOT_FOUND );
		}
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.model.metadata.ObjectDefn#buildDefn()