style: Fix python3 lint issues on servo.
style: Fix python3 lint issues on servo.

Differential Revision: https://phabricator.services.mozilla.com/D35247

splav/servo,DominoTree/servo,KiChjang/servo,nnethercote/servo,splav/servo,KiChjang/servo,nnethercote/servo,notriddle/servo,paulrouget/servo,notriddle/servo,nnethercote/servo,larsbergstrom/servo,paulrouget/servo,larsbergstrom/servo,saneyuki/servo,DominoTree/servo,nnethercote/servo,KiChjang/servo,saneyuki/servo,larsbergstrom/servo,larsbergstrom/servo,splav/servo,splav/servo,saneyuki/servo,DominoTree/servo,notriddle/servo,DominoTree/servo,paulrouget/servo,saneyuki/servo,larsbergstrom/servo,larsbergstrom/servo,KiChjang/servo,KiChjang/servo,DominoTree/servo,larsbergstrom/servo,splav/servo,nnethercote/servo,DominoTree/servo,saneyuki/servo,DominoTree/servo,saneyuki/servo,DominoTree/servo,larsbergstrom/servo,nnethercote/servo,paulrouget/servo,nnethercote/servo,paulrouget/servo,saneyuki/servo,splav/servo,notriddle/servo,DominoTree/servo,notriddle/servo,saneyuki/servo,larsbergstrom/servo,splav/servo,notriddle/servo,nnethercote/servo,nnethercote/servo,DominoTree/servo,nnethercote/servo,notriddle/servo,saneyuki/servo,KiChjang/servo,larsbergstrom/servo,paulrouget/servo,paulrouget/servo,notriddle/servo,splav/servo,KiChjang/servo,paulrouget/servo,paulrouget/servo,saneyuki/servo,KiChjang/servo,KiChjang/servo,paulrouget/servo,notriddle/servo,notriddle/servo,splav/servo,splav/servo,KiChjang/servo