Fix many bugs with closure conversion in checked mode.

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

Index: pkg/kernel/testcases/closures/capture_closure.dart.expect
diff --git a/pkg/kernel/testcases/closures/capture_closure.dart.expect b/pkg/kernel/testcases/closures/capture_closure.dart.expect
index c18b1da7308d817a37ed381a48a16dcd29b9dea8..60196075ae2338f58de3bf044c1450380893294c 100644
--- a/pkg/kernel/testcases/closures/capture_closure.dart.expect
+++ b/pkg/kernel/testcases/closures/capture_closure.dart.expect
@@ -2,14 +2,14 @@ library;
 import self as self;
 
 static method main(dynamic arguments) → dynamic {
-  final Vector #context = MakeVector(3);
+  final dynamic #context = MakeVector(3);
   #context[2] = MakeClosure<() → dynamic>(self::closure#main#f, #context);
   final () → dynamic g = MakeClosure<() → dynamic>(self::closure#main#g, #context);
   g.call();
 }
-static method closure#main#f(Vector #contextParameter) → dynamic {
+static method closure#main#f(dynamic #contextParameter) → dynamic {
   return null;
 }
-static method closure#main#g(Vector #contextParameter) → dynamic {
+static method closure#main#g(dynamic #contextParameter) → dynamic {
   return (#contextParameter[2]).call();
 }