Fix many bugs with closure conversion in checked mode.

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

Index: pkg/kernel/testcases/closures/syncstar.dart.expect
diff --git a/pkg/kernel/testcases/closures/syncstar.dart.expect b/pkg/kernel/testcases/closures/syncstar.dart.expect
index fef5334e3d87b6dd253259092bf4c960e0498539..7407e15d9f931132a242ce7e1f533d95e1bcbc50 100644
--- a/pkg/kernel/testcases/closures/syncstar.dart.expect
+++ b/pkg/kernel/testcases/closures/syncstar.dart.expect
@@ -3,7 +3,7 @@ import self as self;
 import "dart:core" as core;
 
 static method range(core::int high) → dynamic {
-  final Vector #context = MakeVector(3);
+  final dynamic #context = MakeVector(3);
   #context[2] = high;
   final (core::int) → dynamic iter = MakeClosure<(core::int) → dynamic>(self::closure#range#iter, #context);
   return iter;
@@ -16,8 +16,8 @@ static method main() → dynamic {
     throw core::Exception::•("Incorrect output.");
   }
 }
-static method closure#range#iter(Vector #contextParameter, core::int low) → dynamic /* originally sync* */ {
-  final Vector #context = MakeVector(3);
+static method closure#range#iter(dynamic #contextParameter, core::int low) → dynamic /* originally sync* */ {
+  final dynamic #context = MakeVector(3);
   #context[1] = #contextParameter;
   #context[2] = low;
   dynamic :await_jump_var = 0;