Bug 174701 [Viewers] ViewerRow should be reused instead of connected to the Item
Currently we create a ViewerRow ver every Item we create this can degrade performance, we should cache the row and reuse it
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/ColumnViewerEditor.java
private ViewerCell searchCellAboveBelow(ViewerRow row, ColumnViewer viewer,
			int columnIndex, boolean above) {
		ViewerCell rv = null;
		ViewerRow newRow = null;
		if (above) {
			newRow = row.getNeighbor(ViewerRow.ABOVE, false);
		} else {
			newRow = row.getNeighbor(ViewerRow.BELOW, false);
		}
		if (newRow != null) {
			ViewerColumn column = viewer.getViewerColumn(columnIndex);
			if (column != null && column.getEditingSupport() != null
					&& column.getEditingSupport().canEdit(
							newRow.getItem().getData())) {
				rv = newRow.getCell(columnIndex);
			} else {
				rv = searchCellAboveBelow(newRow, viewer, columnIndex, above);
			}
		}
		return rv;
	}
	private ViewerCell searchPreviousCell(ViewerRow row, ColumnViewer viewer,
			int columnIndex, int startIndex) {
		ViewerCell rv = null;
		if (columnIndex - 1 >= 0) {
			ViewerColumn column = viewer.getViewerColumn(columnIndex - 1);
			if (column != null && column.getEditingSupport() != null
					&& column.getEditingSupport().canEdit(
							row.getItem().getData())) {
				rv = row.getCell(columnIndex - 1);