* Revert "libtxt: handle characters encoded as multiple UTF-16 code units (#4165)" This reverts commit5f318a0aa4. * Revert "Proper horizontal a11y scrolling on Android (#4163)" This reverts commit6a74f87210. * Revert "Update Skia revision to 74a8296d7c. (#4164)" This reverts commit7f3c36f42c. * Revert "Revert "Revert engine Dart roll. (#4158)" (#4162)" This reverts commitdf7c8c94d7.