e87326dd7 Suppress an unchecked cast warning in ShimPluginRegistry (flutter/engine#9145) (#33622)

https://github.com/flutter/engine/compare/f6061fb79448...e87326dd7d42

git log f6061fb794486f9d80f6b5281304783b4b45f5e5..e87326dd7d42db415b724c4d206703f971160823 --no-merges --oneline
e87326dd7 Suppress an unchecked cast warning in ShimPluginRegistry (flutter/engine#9145)

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