closure conversion: Support closures in initializers

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

 library;
 import self as self;
 import "dart:core" as core;
 import "dart:mock" as mock;
 
 class C<T extends core::Object, S extends core::Object> extends core::Object {
   constructor internal() → void
     : super core::Object::•()
     ;
   method foo(self::C::S s) → dynamic {
     final mock::Context #context = new mock::Context::•(1);
     #context.parent = null;
     #context.[]=(0, this);
     return new self::Closure#C#foo#function::•<self::C::T, self::C::S>(#context);
   }
+  method bar() → dynamic {
+    self::C<self::C::T, self::C::S> self = this;
+  }
   method baz() → dynamic {
     return new self::Closure#C#baz#function::•<self::C::T, self::C::S>(null);
   }
   static factory •<T extends core::Object, S extends core::Object>() → self::C<self::C::•::T, self::C::•::S> {
     final () → dynamic local = new self::Closure#C#function#local::•<self::C::•::T, self::C::•::S>(null);
     return local.call();
   }
 }
 class Closure#C#foo#function<T extends core::Object, S extends core::Object> extends core::Object implements core::Function {
   field core::String note = "This is temporary. The VM doesn't need closure classes.";
@@ skipping 50 matching lines @@
 static method main(dynamic arguments) → dynamic {
   core::print(self::C::•<core::String, core::String>().foo(null).call(arguments.first));
   dynamic c = self::C::•<core::int, core::int>().baz().call().call();
   if(!(c is self::C<core::int, core::int>))
     throw "${c} fails type test 'is C<int, int>'";
   if(c is self::C<core::String, core::String>) {
     throw "${c} passes type test 'is C<String, String>'";
   }
   core::print(c);
 }