Mozilla: Bad cast in nsImageGeometryMixin (MFSA 2016-85, MFSA 2016-86)

The nsImageGeometryMixin class in Mozilla Firefox before 49.0, Firefox ESR 45.x before 45.4, and Thunderbird 45.4 does not properly perform a cast of an unspecified variable during handling of INPUT elements, which allows remote attackers to execute arbitrary code via a crafted web site...