Bug 153943 [Viewers] Rename new API, e.g. RowPart -> ViewerRow
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/TreeViewer.java
item.addDisposeListener(new DisposeListener() {
				public void widgetDisposed(DisposeEvent e) {
					if (!treeIsDisposed) {
						Object data = item.getData();
						if (usingElementMap() && data != null) {
							unmapElement(data, item);
						}
					}
				}
			});
		}
	}
	
	/* (non-Javadoc)
	 * @see org.eclipse.jface.viewers.ColumnViewer#getRowPartFromItem(org.eclipse.swt.widgets.Widget)
	 */
	protected RowPart getRowPartFromItem(Widget item) {
		RowPart part = (RowPart)item.getData(RowPart.ROWPART_KEY);
		
		if( part == null ) {
			part = new TreeRowPart(((TreeItem)item));
		}
		
		return part;
	}
		
	/**
	 * Create a new RowPart at rowIndex
	 * @param parent
	 * @param style