Revert "Fix closure conversion in field and local initializers."

pkg/kernel/testcases/closures_initializers/local_initializers.dart.expect

 library;
 import self as self;
 import "dart:core" as core;
 
 class X extends core::Object {
   constructor •() → void
     : super core::Object::•()
     ;
 }
 class A extends core::Object {
+  field self::X foo;
+  constructor •(self::X i) → void
+    : self::A::foo = let final Vector #context = MakeVector(2) in let dynamic #t1 = #context[1] = i in (MakeClosure<() → dynamic>(self::closure#A#function#function, #context)).call(), super core::Object::•()
+    ;
+}
+class B extends core::Object {
   field self::X foo = null;
   constructor named(self::X foo) → void
     : super core::Object::•() {}
   constructor •(self::X foo) → void
-    : dynamic extracted#0 = () → self::X
-      throw "Calling unconverted closure at pkg/kernel/testcases/closures_initializers/local_initializers.dart:17:26";
-.call(), this self::A::named(extracted#0)
+    : dynamic extracted#0 = let final Vector #context = MakeVector(2) in let dynamic #t2 = #context[1] = foo in (MakeClosure<() → dynamic>(self::closure#B#function#function, #context)).call(), this self::B::named(extracted#0)
     ;
 }
 static method main() → dynamic {
   self::A a = new self::A::•(new self::X::•());
   a.foo;
+  self::B b = new self::B::•(new self::X::•());
+  b.foo;
 }
+static method closure#A#function#function(Vector #contextParameter) → dynamic {
+  return #contextParameter[1];
+}
+static method closure#B#function#function(Vector #contextParameter) → dynamic {
+  return #contextParameter[1];
+}