Preserve type variables in closure conversion.

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

Index: pkg/kernel/testcases/closures/instance_tear_off.dart.expect
diff --git a/pkg/kernel/testcases/closures/instance_tear_off.dart.expect b/pkg/kernel/testcases/closures/instance_tear_off.dart.expect
index 2d8297742776b0d2a41ec79807736a5008296c6b..4dfa937ae082f5c5097cbea62355bf230533c302 100644
--- a/pkg/kernel/testcases/closures/instance_tear_off.dart.expect
+++ b/pkg/kernel/testcases/closures/instance_tear_off.dart.expect
@@ -50,7 +50,7 @@ class E<T extends core::Object> extends core::Object {
     : super core::Object::•()
     ;
   get g() → dynamic {
-    return MakeClosure<(dynamic) → dynamic>(self::closure#E#g#function, null);
+    return MakeClosure<<T extends core::Object>(self::closure#E#g#function::T) → dynamic, self::E::T>(self::closure#E#g#function, null);

[Dmitry Stefantsov, 2017/07/25 09:13:34]

The first type parameter of MakeClosure (i.e. the function type of the closure)
here doesn't look right.  The type of the function parameter should refer to the
type parameter defined to the left of it, not to the type parameter of some
(although, related) top-level function.

[sjindel, 2017/07/25 13:11:48]

It does actually refer to the parameter on the left, because they are the same
pointer. It's just the textual printing that's confusing here, because the same
type parameter pointer is reused below for the top-level function definition.
This is problematic because it violates the tree property though, so I've fixed
it by creating new parameters for the closure's type.

[Dmitry Stefantsov, 2017/07/26 09:12:09]

Thank you for the explanation!

   }
   method a() → dynamic {
     return "a";
@@ -107,7 +107,7 @@ static method closure#D#g#function(Vector #contextParameter, dynamic x) → dyna
 static method closure#D#f#function(Vector #contextParameter) → dynamic {
   return "f";
 }
-static method closure#E#g#function(Vector #contextParameter, dynamic x) → dynamic {
+static method closure#E#g#function<T extends core::Object>(Vector #contextParameter, self::closure#E#g#function::T x) → dynamic {
   return "g(${x})";
 }
 static method closure#E#f#function(Vector #contextParameter) → dynamic {