Roll engine de420a0fc49a..4d6847466d0b (3 commits) (#34258)

https://github.com/flutter/engine/compare/de420a0fc49a...4d6847466d0b

git log de420a0fc49ac5d8d84e3dd446af800d672eff02..4d6847466d0b8223f2d3ba9572e397306b6debf4 --no-merges --oneline
4d6847466 Load AOT compiled Dart assets only from ELF libraries (flutter/engine#9260)
3e9ffe113 Whitelist the —enable_mirrors flag to fix regression in existing embedder. (flutter/engine#9266)
7cde42cc1 Unbreak internal rolls (flutter/engine#9270)

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bin/internal/engine.version

-de420a0fc49ac5d8d84e3dd446af800d672eff02
+4d6847466d0b8223f2d3ba9572e397306b6debf4