Bug 199834 Enable access to IContent object in IReportItemPresentation layer
In IReportItemPresentation layer, the extended item may want to access properties from current IContent object, for example, bookmark, content style. So we need expose the content object in this layer.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/extension/IReportItemGeneration.java
/**
	 * pass the prepared query definition to extended item implementation, so
	 * that it can access data.
	 */
	public void setReportQueries( IBaseQueryDefinition[] queries );
	/**
	 * processes the extended item in report generation environment.
	 * 
	 * @param rowSets
	 *            rowSets an array of row sets that is passed to the extension
	 * @return an object that captures the generation-time state information
	 *         about the extended item. Presentation engine guarantees that the
	 *         same object is returned to the extended item instance at
	 *         presentation time. To achieve such a goal, generation engine may
	 *         uses serialization services provided by the
	 *         IReportItemSerializable interface.
	 * @throws BirtException
	 *             throws exception when there is a problem processing the
	 *             extended item
	 */
	public abstract void onRowSets( IRowSet[] rowSets ) throws BirtException;
	/**
	 * returns whether the extended item needs serialization of state
	 * information at generation time
	 * 
	 * @return whether the extended item needs to serialize state information at
	 *         generation time
	 */
	public abstract boolean needSerialization( );
	/**