refactor remove deprecated usage of expandos in DomElementWrapper
refactor remove deprecated usage of expandos in DomElementWrapper

DomElementWrapper.getData() no longer internally checks for expandos
prefixed with '_'. Please use 'data-' prefix for expandos.

Most of the related code was removed in AT 1.3.1, this is just leftovers
that were omitted that time.

fcapa/aria,benouat/ariatemplates,simonarbuckle/ariatemplates,ymeine/ariatemplates,lsimone/ariatemplates,fcapa/aria,simonarbuckle/ariatemplates,fbasso/ariatemplates,benouat/ariatemplates,mlaval/ariatemplates,vcarle/ariatemplates,ymeine/ariatemplates,vcarle/ariatemplates,ariatemplates/ariatemplates,simonarbuckle/ariatemplates,lsimone/ariatemplates,ariatemplates/ariatemplates,divdavem/ariatemplates,mlaval/ariatemplates,fbasso/ariatemplates,fcapa/aria,benouat/ariatemplates,vcarle/ariatemplates,divdavem/ariatemplates,fbasso/ariatemplates,flongo/ariatemplates,ariatemplates/ariatemplates,mlaval/ariatemplates,divdavem/ariatemplates,ymeine/ariatemplates