closure conversion: Support closures in initializers

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

+library;
+import self as self;
+import "dart:core" as core;
+import "dart:mock" as mock;
+
+class C extends core::Object {
+  field dynamic t;
+  constructor foo(dynamic f) → void
+    : self::C::t = let final mock::Context #context = new mock::Context::•(1) in let dynamic #t1 = #context.[]=(0, f) in new self::Closure#C#foo#function::•(#context), super core::Object::•() {
+    final mock::Context #context = new mock::Context::•(1);
+    #context.parent = null;
+    #context.[]=(0, f);
+    core::print(1);
+  }
+}
+class Closure#C#foo#function extends core::Object implements core::Function {
+  field core::String note = "This is temporary. The VM doesn't need closure classes.";
+  field mock::Context context;
+  constructor •(final mock::Context context) → dynamic
+    : self::Closure#C#foo#function::context = context
+    ;
+  method call() → dynamic {
+    "This is a temporary solution. In the VM, this will become an additional parameter.";
+    final mock::Context #contextParameter = this.{self::Closure#C#foo#function::context};
+    return #contextParameter.[](0).call();
+  }
+}
+class Closure#main#function extends core::Object implements core::Function {
+  field core::String note = "This is temporary. The VM doesn't need closure classes.";
+  field mock::Context context;
+  constructor •(final mock::Context context) → dynamic
+    : self::Closure#main#function::context = context
+    ;
+  method call() → dynamic {
+    "This is a temporary solution. In the VM, this will become an additional parameter.";
+    final mock::Context #contextParameter = this.{self::Closure#main#function::context};
+    return core::print("hest");
+  }
+}
+static method main() → dynamic {
+  core::print(0);
+  dynamic c = new self::C::foo(new self::Closure#main#function::•(null));
+  core::print(2);
+  c.t();
+  core::print(3);
+}