Lift nearly all top-level type inference restrictions.

pkg/front_end/testcases/inference_new/infer_assign_to_ref.dart.strong.expect

Index: pkg/front_end/testcases/inference_new/infer_assign_to_ref.dart.strong.expect
diff --git a/pkg/front_end/testcases/inference/infer_assign_to_ref.dart.strong.expect b/pkg/front_end/testcases/inference_new/infer_assign_to_ref.dart.strong.expect
similarity index 90%
copy from pkg/front_end/testcases/inference/infer_assign_to_ref.dart.strong.expect
copy to pkg/front_end/testcases/inference_new/infer_assign_to_ref.dart.strong.expect
index a97346c7d6e1c7a7d7cf0299dc11e092b8a0fd02..7736f28b3cca8d2043334d5c84854bb32c3ba74e 100644
--- a/pkg/front_end/testcases/inference/infer_assign_to_ref.dart.strong.expect
+++ b/pkg/front_end/testcases/inference_new/infer_assign_to_ref.dart.strong.expect
@@ -11,7 +11,7 @@ class A extends core::Object {
 static field self::A a = new self::A::•();
 static field dynamic b = self::a.{self::A::f} = 1;
 static field core::int c = 0;
-static field dynamic d = self::c = 1;
+static field core::int d = self::c = 1;
 static method main() → dynamic {
   self::a;
   self::b;