Bug 121687 Exception throws when export data in table which inside a grid cell.
Description: Exception throws when export data in table which inside a grid cell. Steps to reproduce: 1. insert a grid. 2. insert one table to one grid cell. 3. insert another table to the other grid cell. 4. export data in two tables. Expected result: Data are exported. Actual result: Exception in: ReportEngineService.getMetaData( )
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/parser/EngineIRVisitor.java
if ( modelOpr.equals( DesignChoiceConstants.FILTER_OPERATOR_LE ) )
			return IConditionalExpression.OP_LE;
		if ( modelOpr.equals( DesignChoiceConstants.FILTER_OPERATOR_GE ) )
			return IConditionalExpression.OP_GE;
		if ( modelOpr.equals( DesignChoiceConstants.FILTER_OPERATOR_GT ) )
			return IConditionalExpression.OP_GT;
		if ( modelOpr.equals( DesignChoiceConstants.FILTER_OPERATOR_BETWEEN ) )
			return IConditionalExpression.OP_BETWEEN;
		if ( modelOpr
				.equals( DesignChoiceConstants.FILTER_OPERATOR_NOT_BETWEEN ) )
			return IConditionalExpression.OP_NOT_BETWEEN;
		if ( modelOpr.equals( DesignChoiceConstants.FILTER_OPERATOR_NULL ) )
			return IConditionalExpression.OP_NULL;
		if ( modelOpr.equals( DesignChoiceConstants.FILTER_OPERATOR_NOT_NULL ) )
			return IConditionalExpression.OP_NOT_NULL;
		if ( modelOpr.equals( DesignChoiceConstants.FILTER_OPERATOR_TRUE ) )
			return IConditionalExpression.OP_TRUE;
		if ( modelOpr.equals( DesignChoiceConstants.FILTER_OPERATOR_FALSE ) )
			return IConditionalExpression.OP_FALSE;
		if ( modelOpr.equals( DesignChoiceConstants.FILTER_OPERATOR_LIKE ) )
			return IConditionalExpression.OP_LIKE;
		if ( modelOpr.equals( DesignChoiceConstants.FILTER_OPERATOR_TOP_N ) )
			return IConditionalExpression.OP_TOP_N;
		if ( modelOpr.equals( DesignChoiceConstants.FILTER_OPERATOR_BOTTOM_N ) )
			return IConditionalExpression.OP_BOTTOM_N;
		if ( modelOpr
				.equals( DesignChoiceConstants.FILTER_OPERATOR_TOP_PERCENT ) )
			return IConditionalExpression.OP_TOP_PERCENT;
		if ( modelOpr
				.equals( DesignChoiceConstants.FILTER_OPERATOR_BOTTOM_PERCENT ) )