Fix many bugs with closure conversion in checked mode.

pkg/kernel/testcases/closures/uncaptured_for_in_loop.dart.expect

Index: pkg/kernel/testcases/closures/uncaptured_for_in_loop.dart.expect
diff --git a/pkg/kernel/testcases/closures/uncaptured_for_in_loop.dart.expect b/pkg/kernel/testcases/closures/uncaptured_for_in_loop.dart.expect
index 3a044c89aa3f49ce2d9cc6664b6417f762d26071..84f45e3fd0e95d5134379a97b9a1a9cd599d97fa 100644
--- a/pkg/kernel/testcases/closures/uncaptured_for_in_loop.dart.expect
+++ b/pkg/kernel/testcases/closures/uncaptured_for_in_loop.dart.expect
@@ -6,7 +6,7 @@ static const field dynamic numbers = const <core::int>[0, 1, 2, 3, 4, 5, 6, 7, 8
 static method main() → dynamic {
   dynamic closures = <dynamic>[];
   for (core::int i in self::numbers) {
-    final Vector #context = MakeVector(3);
+    final dynamic #context = MakeVector(3);
     #context[2] = i;
     closures.add(MakeClosure<() → dynamic>(self::closure#main#function, #context));
   }
@@ -19,6 +19,6 @@ static method main() → dynamic {
     throw core::Exception::•("Unexpected sum = ${sum} != ${expectedSum}");
   }
 }
-static method closure#main#function(Vector #contextParameter) → dynamic {
+static method closure#main#function(dynamic #contextParameter) → dynamic {
   return #contextParameter[2];
 }