Eliminate type mismatch between PluginImpl and IBidiPlugin caused by sideways-cast.
Eliminate type mismatch between PluginImpl and IBidiPlugin caused by sideways-cast.

This allows the properties of PluginImpl to be disambiguated.
RELNOTES: n/a
PiperOrigin-RevId: 367312074

google/closure-library,google/closure-library,google/closure-library,google/closure-library,google/closure-library