Roll engine ef2bed65db22..39a950e5d1d1 (5 commits) (#32011)

https://github.com/flutter/engine/compare/ef2bed65db22...39a950e5d1d1

git log ef2bed65db22b1ce3d05947d5cfa3927eb6fa975..39a950e5d1d1cbeb3d70334c6275d224e843b30e --no-merges --oneline
39a950e5d remove legacy build deps (flutter/engine#8820)
c0be4e277 Fix api conformance check (flutter/engine#8817)
30639ee7b Allow FlutterEngine to be used on back-to-back screens (#31264). (flutter/engine#8808)
45d0c4d11 Roll src/third_party/skia cd5d14619fe2..68eb8c276355 (4 commits) (flutter/engine#8815)
9856479ec Roll src/third_party/dart b6997deb3e..1577b95c93 (18 commits)

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bin/internal/engine.version

-ef2bed65db22b1ce3d05947d5cfa3927eb6fa975
+39a950e5d1d1cbeb3d70334c6275d224e843b30e