Bug 151552 Can't change the Data Set of a chart drag from a library
After creating a library with a chart,you use it and drag the chart to a report design.A error happen when you change the Data Set of the chart. 1.creat a library,add a chart into it ,then publish the library. 2.new a report and use the library ,drag the chart into the layout of the report,you can't change the data set of the chart,or a error will occur. Actual result:A error occur when you change the data set] Expected result:You can change the data set.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/core/PropertySearchStrategy.java
* gets the "effective" property value. The definition can be for a system
	 * or user-defined property.
	 * <p>
	 * The search won't search up the containment hierarchy. Meanwhile, it won't
	 * the inheritance hierarchy if the non-style property is not inheritable.
	 * <p>
	 * Part of: Property value system.
	 * 
	 * @param module
	 *            the module
	 * @param element
	 *            the element to search
	 * @param prop
	 *            definition of the property to get
	 * @return The property value, or null if no value is set.
	 */
	public Object getPropertyFromElement( Module module, DesignElement element,
			ElementPropertyDefn prop )
	{
		Object value = null;
		value = getPropertyFromSelf( module, element, prop );
		if ( value != null )
			return value;
		
		
		
		if ( isInheritableProperty( element, prop ) || prop.isStyleProperty( ) )
		{
			value = getPropertyFromParent( element, prop );
			if ( value != null )