[migration] fix bug in `CWAttributeAddOp.revertprecommit_event`
The `rdefdef` attribute is set during the operation execution. In some the
operation crash before this assignment. In such case `revertprecommit` raise an
attribute error crashing the whole process and shadowing the original error.
This changeset detect and Avoid this situation.
$(document).ready(function(){module("module2",{setup:function(){$('#main').append('<select id="theselect" multiple="multiple" size="2">'+'</select>');}});test("test first selected",function(){$('#theselect').append('<option value="foo">foo</option>'+'<option selected="selected" value="bar">bar</option>'+'<option value="baz">baz</option>'+'<option selected="selecetd"value="spam">spam</option>');varselected=firstSelected(document.getElementById("theselect"));equals(selected.value,'bar');});test("test first selected 2",function(){$('#theselect').append('<option value="foo">foo</option>'+'<option value="bar">bar</option>'+'<option value="baz">baz</option>'+'<option value="spam">spam</option>');varselected=firstSelected(document.getElementById("theselect"));equals(selected,null);});module("visibilty");test('toggleVisibility',function(){$('#main').append('<div id="foo"></div>');toggleVisibility('foo');ok($('#foo').hasClass('hidden'),'check hidden class is set');});});