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<() → core::String>(self::closure#C#f#function, null);
-  constructor •() → void
+  field dynamic f = MakeClosure<() → dynamic>(self::closure#C#f#function, null);
+  default constructor •() → void
     : super core::Object::•()
     ;
   get g() → dynamic {
-    return MakeClosure<(dynamic) → core::String>(self::closure#C#g#function, null);
+    return MakeClosure<(dynamic) → dynamic>(self::closure#C#g#function, null);
   }
   method a() → dynamic {
     return "a";
   }
   method b(dynamic x) → dynamic {
     return x;
   }
   method c(dynamic x, [dynamic y = 2]) → dynamic {
     return x.+(y);
   }
   method d(dynamic x, {dynamic y = 2}) → dynamic {
     return x.+(y);
   }
 }
 class D<T extends core::Object> extends core::Object {
-  field dynamic f = MakeClosure<() → core::String>(self::closure#D#f#function, null);
-  constructor •() → void
+  field dynamic f = MakeClosure<() → dynamic>(self::closure#D#f#function, null);
+  default constructor •() → void
     : super core::Object::•()
     ;
   get g() → dynamic {
-    return MakeClosure<(dynamic) → core::String>(self::closure#D#g#function, null);
+    return MakeClosure<(dynamic) → dynamic>(self::closure#D#g#function, null);
   }
   method a() → dynamic {
     return "a";
   }
   method b(dynamic x) → dynamic {
     return x;
   }
   method c(dynamic x, [dynamic y = 2]) → dynamic {
     return x.+(y);
   }
   method d(dynamic x, {dynamic y = 2}) → dynamic {
     return x.+(y);
   }
 }
 class E<T extends core::Object> extends core::Object {
-  field dynamic f = MakeClosure<() → core::String>(self::closure#E#f#function, null);
-  constructor •() → void
+  field dynamic f = MakeClosure<() → dynamic>(self::closure#E#f#function, null);
+  default constructor •() → void
     : super core::Object::•()
     ;
   get g() → dynamic {
-    return MakeClosure<(dynamic) → core::String>(self::closure#E#g#function, null);
+    return MakeClosure<(dynamic) → dynamic>(self::closure#E#g#function, null);
   }
   method a() → dynamic {
     return "a";
   }
   method b(self::E::T x) → dynamic {
     return x;
   }
   method c(self::E::T x, [self::E::T y = 2]) → dynamic {
     return x.+(y);
   }
@@ skipping 24 matching lines @@
   self::expect(42, o.d(40));
   self::expect(42, o.d.call(40));
   self::expect(87, o.d(80, y: 7));
   self::expect(87, o.d.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) → core::String {
+static method closure#C#g#function(Vector #contextParameter, dynamic x) → dynamic {
   return "g(${x})";
 }
-static method closure#C#f#function(Vector #contextParameter) → core::String {
+static method closure#C#f#function(Vector #contextParameter) → dynamic {
   return "f";
 }
-static method closure#D#g#function(Vector #contextParameter, dynamic x) → core::String {
+static method closure#D#g#function(Vector #contextParameter, dynamic x) → dynamic {
   return "g(${x})";
 }
-static method closure#D#f#function(Vector #contextParameter) → core::String {
+static method closure#D#f#function(Vector #contextParameter) → dynamic {
   return "f";
 }
-static method closure#E#g#function(Vector #contextParameter, dynamic x) → core::String {
+static method closure#E#g#function(Vector #contextParameter, dynamic x) → dynamic {
   return "g(${x})";
 }
-static method closure#E#f#function(Vector #contextParameter) → core::String {
+static method closure#E#f#function(Vector #contextParameter) → dynamic {
   return "f";
 }