Convert closures in all initializers, and share the context between them.

pkg/kernel/testcases/closures_initializers/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::•()
+    : final Vector #context = MakeVector(2), dynamic #t1 = #context[1] = i, self::A::foo = (MakeClosure<() → dynamic>(self::closure#A#function#function, #context)).call(), super core::Object::•()
+    ;
+}
+class S extends self::A {
+  constructor •(self::X i) → void
+    : final Vector #context = MakeVector(2), dynamic #t2 = #context[1] = i, super self::A::•((MakeClosure<() → dynamic>(self::closure#S#function#function, #context)).call())
+    ;
+}
+class S2 extends core::Object {
+  field self::X foo;
+  constructor •(self::X foo) → void
+    : self::S2::foo = foo, super core::Object::•()
+    ;
+  constructor wat(self::X i) → void
+    : final Vector #context = MakeVector(2), dynamic #t3 = #context[1] = i, dynamic extracted#0 = (MakeClosure<() → dynamic>(self::closure#S2#wat#function, #context)).call(), this self::S2::•(extracted#0)
     ;
 }
 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 = 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)
+    : final Vector #context = MakeVector(2), dynamic #t4 = #context[1] = foo, dynamic extracted#0 = (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;
+  self::S s = new self::S::•(new self::X::•());
+  s.foo;
+  self::S2 s2 = new self::S2::•(new self::X::•());
+  s2.foo;
 }
 static method closure#A#function#function(Vector #contextParameter) → dynamic {
   return #contextParameter[1];
 }
+static method closure#S#function#function(Vector #contextParameter) → dynamic {
+  return #contextParameter[1];
+}
+static method closure#S2#wat#function(Vector #contextParameter) → dynamic {
+  return #contextParameter[1];
+}
 static method closure#B#function#function(Vector #contextParameter) → dynamic {
   return #contextParameter[1];
 }