Bug 156166 Error occour when previewing attached report in web viewer.
Decription:Error occour when previewing attached report in web viewer. Steps to reproduce: 1.run attached reports in web viewer. Expeceted results: preview properly Actual results: Error occour when previewing the reports in web viewer while it works properly in html and PDF
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/impl/document/RowSaveUtil.java
this.exprNameSet = exprNameSet;
	}
	/**
	 * @param currIndex
	 * @param valueMap
	 * @throws DataException
	 */
	void saveExprValue( int currIndex, Map valueMap )
			throws DataException
	{
		try
		{
			initSave( false );
			
			saveNullRowsBetween( lastRowIndex, currIndex );
			
			int rowBytes = saveExprValue( valueMap );
			IOUtil.writeInt( this.rowLenDos, currentOffset );
			currentOffset += rowBytes;
			lastRowIndex = currIndex;
		}
		catch ( IOException e )
		{
			throw new DataException( ResourceConstants.RD_SAVE_ERROR,
					e,
					"Result Data" );
		}
	}
	
	/**