Bug 162167 Add API IResultIterator.isEmpty to Data Engine.
Current DTE api do not have a method that can be directly used to tell the client whether an IResultIterator is empty or not.We need to add this api for the convenience sake.
engine/org.eclipse.birt.report.engine.tests/test/org/eclipse/birt/report/engine/api/script/RowDataTest.java
public Integer getInteger( IBaseExpression dataExpr )
				throws BirtException
		{
			return null;
		}
		public Double getDouble( IBaseExpression dataExpr )
				throws BirtException
		{
			return null;
		}
		public String getString( IBaseExpression dataExpr )
				throws BirtException
		{
			return null;
		}
		public BigDecimal getBigDecimal( IBaseExpression dataExpr )
				throws BirtException
		{
			return null;
		}
		public Date getDate( IBaseExpression dataExpr ) throws BirtException
		{
			return null;
		}
		public Blob getBlob( IBaseExpression dataExpr ) throws BirtException
		{
			return null;
		}
		public byte[] getBytes( IBaseExpression dataExpr ) throws BirtException
		{