Corrected the inaccurate description of 'DRFSorter::dirty'.
Corrected the inaccurate description of 'DRFSorter::dirty'.

Review: https://reviews.apache.org/r/37289

verizonlabs/mesos,gsantovena/mesos,jpeach/mesos,chhsia0/mesos,neilconway/mesos,abudnik/mesos,asamerh4/mesos,andschwa/mesos,abudnik/mesos,asamerh4/mesos,andschwa/mesos,abudnik/mesos,dforsyth/mesos,kaysoky/mesos,gsantovena/mesos,gsantovena/mesos,andschwa/mesos,jpeach/mesos,reneploetz/mesos,Gilbert88/mesos,Aman-Jain-14/customizedMesos,dforsyth/mesos,Gilbert88/mesos,reneploetz/mesos,kaysoky/mesos,asamerh4/mesos,zmalik/mesos,kaysoky/mesos,craimbert/mesos,zmalik/mesos,Aman-Jain-14/customizedMesos,kaysoky/mesos,Aman-Jain-14/customizedMesos,craimbert/mesos,jpeach/mesos,Aman-Jain-14/customizedMesos,kaysoky/mesos,verizonlabs/mesos,chhsia0/mesos,verizonlabs/mesos,Gilbert88/mesos,neilconway/mesos,zmalik/mesos,jpeach/mesos,kaysoky/mesos,verizonlabs/mesos,neilconway/mesos,neilconway/mesos,Gilbert88/mesos,yuquanshan/customizedMesos,yuquanshan/customizedMesos,verizonlabs/mesos,neilconway/mesos,gsantovena/mesos,Gilbert88/mesos,asamerh4/mesos,yuquanshan/customizedMesos,andschwa/mesos,asamerh4/mesos,craimbert/mesos,neilconway/mesos,asamerh4/mesos,abudnik/mesos,reneploetz/mesos,Aman-Jain-14/customizedMesos,dforsyth/mesos,zmalik/mesos,yuquanshan/customizedMesos,andschwa/mesos,neilconway/mesos,reneploetz/mesos,gsantovena/mesos,craimbert/mesos,gsantovena/mesos,verizonlabs/mesos,Aman-Jain-14/customizedMesos,kaysoky/mesos,Aman-Jain-14/customizedMesos,jpeach/mesos,chhsia0/mesos,verizonlabs/mesos,andschwa/mesos,chhsia0/mesos,chhsia0/mesos,jpeach/mesos,yuquanshan/customizedMesos,abudnik/mesos,zmalik/mesos,reneploetz/mesos,asamerh4/mesos,andschwa/mesos,dforsyth/mesos,zmalik/mesos,abudnik/mesos,reneploetz/mesos,dforsyth/mesos,dforsyth/mesos,Gilbert88/mesos,craimbert/mesos,jpeach/mesos,yuquanshan/customizedMesos,gsantovena/mesos,craimbert/mesos,chhsia0/mesos,zmalik/mesos,abudnik/mesos,dforsyth/mesos,chhsia0/mesos,yuquanshan/customizedMesos,craimbert/mesos,reneploetz/mesos,Gilbert88/mesos