[550436] Fix tabs order algorithm The algorithm processing 'afterTab' elements was bugged and leaded to have wrong tabs order. Also add test cases. Bug: https://bugs.eclipse.org/bugs/show_bug.cgi?id=550436 Change-Id: Idf802fdc0a0812486d279395751d138e0b3ccf50 Signed-off-by: Axel RICHARD <axel.richard@obeo.fr>