Bug 195607 NPE is thrown when calling DimensionHandle:: getAbsoluteValue()
If a DimensionHandle did not set DimensionValue, NPE will thrown when calling DimensionHandle:: getAbsoluteValue().
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/DimensionHandle.java
* @param element
	 *            the design element handle
	 * @param memberRef
	 *            the memberRef for the member property
	 */
	public DimensionHandle( DesignElementHandle element, MemberRef memberRef )
	{
		super( element, memberRef );
		assert memberRef.getMemberDefn( ).getType( ) instanceof DimensionPropertyType;
	}
	/**
	 * Constructs a dimension handle for a element property. This property must
	 * be a dimension type.
	 * 
	 * @param element
	 *            handle to the element that defined the property.
	 * @param thePropDefn
	 *            definition of the dimension property.
	 */
	public DimensionHandle( DesignElementHandle element,
			ElementPropertyDefn thePropDefn )
	{
		super( element, thePropDefn );
		assert thePropDefn.getType( ) instanceof DimensionPropertyType;
	}
	/**
	 * Determines if the dimension is given by a standard format or by a
	 * pre-defined constant.
	 * 
	 * @return <code>true</code> if the dimension is given by an pre-defined