The result to CompleteEmpty() being called on the platform message (#28407)
The result to CompleteEmpty() being called on the platform message (#28407)

response is being interpreted as `null` in dart. This results in a
MissingPluginException being thrown whenever `View.update` or
`View.dispose` is invoked.

This change returns null data in a dictionary to complete the response
in a way that is not interpreted as `null` in dart.
jason-simmons/flutter_engine,Hixie/sky_engine,devoncarew/engine,chinmaygarde/flutter_engine,chinmaygarde/flutter_engine,Hixie/sky_engine,aam/engine,rmacnak-google/engine,chinmaygarde/flutter_engine,devoncarew/engine,aam/engine,jason-simmons/flutter_engine,Hixie/sky_engine,Hixie/sky_engine,chinmaygarde/flutter_engine,Hixie/sky_engine,aam/engine,chinmaygarde/flutter_engine,aam/engine,jason-simmons/flutter_engine,flutter/engine,flutter/engine,flutter/engine,rmacnak-google/engine,devoncarew/engine,devoncarew/engine,rmacnak-google/engine,rmacnak-google/engine,aam/engine,flutter/engine,jason-simmons/flutter_engine,rmacnak-google/engine,jason-simmons/flutter_engine,devoncarew/engine,flutter/engine,jason-simmons/flutter_engine,aam/engine,aam/engine,flutter/engine,aam/engine,Hixie/sky_engine,jason-simmons/flutter_engine,chinmaygarde/flutter_engine,jason-simmons/flutter_engine,flutter/engine,rmacnak-google/engine,Hixie/sky_engine,rmacnak-google/engine,flutter/engine,devoncarew/engine,chinmaygarde/flutter_engine,Hixie/sky_engine,devoncarew/engine