Add support for converted closures with explicit contexts to VM

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

Index: pkg/kernel/testcases/closures/capture_this.dart.expect
diff --git a/pkg/kernel/testcases/closures/capture_this.dart.expect b/pkg/kernel/testcases/closures/capture_this.dart.expect
index 04eaabeab53cff435158e3250f054dbf24ce17e7..35cfbf40960e730533aa72659cc25783e3b93b9f 100644
--- a/pkg/kernel/testcases/closures/capture_this.dart.expect
+++ b/pkg/kernel/testcases/closures/capture_this.dart.expect
@@ -4,7 +4,7 @@ import "dart:core" as core;
 
 class C extends core::Object {
   field dynamic x = null;
-  constructor •() → void
+  default constructor •() → void
     : super core::Object::•()
     ;
   method m() → dynamic {
@@ -15,7 +15,7 @@ class C extends core::Object {
   method f() → dynamic {
     final Vector #context = MakeVector(2);
     #context[1] = this;
-    return MakeClosure<() → () → dynamic>(self::closure#C#f#function, #context);
+    return MakeClosure<() → dynamic>(self::closure#C#f#function, #context);
   }
 }
 static method main() → dynamic {
@@ -34,6 +34,6 @@ static method closure#C#m#function(Vector #contextParameter, dynamic v) → dyna
 static method closure#C#f#function#function(Vector #contextParameter) → dynamic {
   return (#contextParameter[1]).x;
 }
-static method closure#C#f#function(Vector #contextParameter) → () → dynamic {
+static method closure#C#f#function(Vector #contextParameter) → dynamic {
   return MakeClosure<() → dynamic>(self::closure#C#f#function#function, #contextParameter);
 }