Bug 1018720 - Switch the translation infobar select box icon and add a HiDPI variant. r=florian

--HG--
extra : rebase_source : ca98e16a58e5ea2d16b48fa5a678008f268202c0
extra : histedit_source : 141dc4c7baca51e1eec06838a42c88f9471b28e3
Bug 1018720 - Fix translation infobar button styling. r=florian

--HG--
extra : rebase_source : 27ee6b3d8555e96fd72936118a6a599fab8da64a
extra : histedit_source : e935ce68b124e328e4e9a65abc403caf221eeac3
Bug 1018720 - Change the translation infobar select dropdown styling to match the options dropdown. r=florian

--HG--
extra : rebase_source : 3be092aa43b1356728f3a9064cb49949c75bab50
extra : histedit_source : b55c90b6cb24f3795e3848652cd0980bb645b098
Bug 1018720 - Change the options dropdown icon to match the select dropdown. r=florian

--HG--
extra : rebase_source : d7d7eb6d00158219c4113ecbaf958649f13692eb
extra : histedit_source : 77d847c52f3dc563b8f13343c0720500cebc422c