Small fixes to top level type inference.

pkg/front_end/testcases/inference_new/downwards_inference_inside_top_level.dart.direct.expect

 library test;
 import self as self;
 import "dart:core" as core;
 
 class A extends core::Object {
   field self::B<core::int> b = null;
   constructor •() → void
     : super core::Object::•()
     ;
 }
 class B<T extends core::Object> extends core::Object {
   constructor •(self::B::T x) → void
     : super core::Object::•()
     ;
 }
-static field self::A t1 = let final self::A #t1 = new self::A::•() in let final dynamic #t2 = #t1.{self::A::b} = new self::B::•<core::int>(1) in #t1;
-static field core::List<self::B<core::int>> t2 = <self::B<core::int>>[new self::B::•<core::int>(2)];
-static field core::List<self::B<dynamic>> t3 = <self::B<dynamic>>[new self::B::•<dynamic>(3)];
+static field dynamic t3 = <dynamic>[new self::B::•<dynamic>(3)];
 static method main() → dynamic {}