The Flutter engine startup hooks need to pass the correct type of arguments

[a-siva]

With change
dart/9f00eec55b [ VM / Mirrors ] Added type checking to enforce strong mode semantics when using dart:mirrors / Dart API
The Dart VM checks for strong mode semantics when the Dart API methods to invoke methods is used.

Currently the Flutter engine during initialization does not pass the correct type for List arguments in some cases, e.g:
void _updateLocales(List<String> locales) {
Has a signature that accepts List

But the call to it from the engine uses a List for the locales argument

  DartInvokeField(library_.value(), "_updateLocales",
                  {
                      tonic::ToDart<std::vector<std::string>>(locales),
                  });

This results in a runtime exception

[ +295 ms] Shell: [ERROR:flutter/shell/common/shell.cc(182)] Dart Error:
Unhandled exception:
[        ] Shell: type 'List<dynamic>' is not a subtype of type 'List<String>'
of 'locales'
[        ] Shell: #0      _TypeError._throwNew (dart:core/runtime/liberrors_patch.dart:89:75)

and the code in updateLocales is not executed at all.

[a-siva]

/cc @jason-simmons

[aartbik]

@aartbik for dart roll

[github-actions]

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