Add support for converted closures with explicit contexts to VM

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

 library;
 import self as self;
 import "dart:core" as core;
 
 class C extends core::Object {
   field dynamic f = MakeClosure<() → dynamic>(self::closure#C#f#function, null);
   constructor •() → void
     : super core::Object::•()
     ;
   get g() → dynamic {
@@ skipping 120 matching lines @@
     core::print("Expected '${expected}' but got '${actual}'");
     throw "Expected '${expected}' but got '${actual}'";
   }
 }
 static method test(dynamic o) → dynamic {
   self::expect("f", o.f());
   self::expect("f", o.f.call());
   self::expect("g(42)", o.g(42));
   self::expect("g(42)", o.g.call(42));
   self::expect("a", o.a());
-  self::expect("a", o.a#get().call());
+  self::expect("a", o.a#get.call());
   self::expect(42, o.b(42));
-  self::expect(42, o.b#get().call(42));
+  self::expect(42, o.b#get.call(42));
   self::expect(42, o.c(40));
-  self::expect(42, o.c#get().call(40));
+  self::expect(42, o.c#get.call(40));
   self::expect(87, o.c(80, 7));
-  self::expect(87, o.c#get().call(80, 7));
+  self::expect(87, o.c#get.call(80, 7));
   self::expect(42, o.d(40));
-  self::expect(42, o.d#get().call(40));
+  self::expect(42, o.d#get.call(40));
   self::expect(87, o.d(80, y: 7));
-  self::expect(87, o.d#get().call(80, y: 7));
+  self::expect(87, o.d#get.call(80, y: 7));
 }
 static method main(dynamic arguments) → dynamic {
   self::test(new self::C::•());
   self::test(new self::D::•<core::int>());
   self::test(new self::E::•<core::int>());
 }
 static method closure#C#g#function(Vector #contextParameter, dynamic x) → dynamic {
   return "g(${x})";
 }
 static method closure#C#a(Vector #contextParameter) → dynamic
@@ skipping 28 matching lines @@
   return (#contextParameter[1]).{self::E::a}();
 static method closure#E#b(Vector #contextParameter, dynamic x) → dynamic
   return (#contextParameter[1]).{self::E::b}(x);
 static method closure#E#c(Vector #contextParameter, dynamic x, [dynamic y = 2]) → dynamic
   return (#contextParameter[1]).{self::E::c}(x, y);
 static method closure#E#d(Vector #contextParameter, dynamic x, {dynamic y = 2}) → dynamic
   return (#contextParameter[1]).{self::E::d}(x, y: y);
 static method closure#E#f#function(Vector #contextParameter) → dynamic {
   return "f";
 }