Revert "fix #27256, track type bounds for generic functions"

pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/rtti.dart

Index: pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/rtti.dart
diff --git a/pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/rtti.dart b/pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/rtti.dart
index 39a350fd9b76352664853c398f4aec741e233c25..fd7c515c1558a770065cd566f2ebf47feea6a330 100644
--- a/pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/rtti.dart
+++ b/pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/rtti.dart
@@ -58,7 +58,7 @@ part of dart._runtime;
 fn(closure, t) {
   if (t == null) {
     // No type arguments, it's all dynamic
-    t = fnType(JS('', '#', dynamic),
+    t = definiteFunctionType(JS('', '#', dynamic),
         JS('', 'Array(#.length).fill(#)', closure, dynamic), JS('', 'void 0'));
   }
   tag(closure, t);
@@ -111,7 +111,7 @@ _checkPrimitiveType(obj) {
 getFunctionType(obj) {
   // TODO(vsm): Encode this properly on the function for Dart-generated code.
   var args = JS('', 'Array(#.length).fill(#)', obj, dynamic);
-  return fnType(bottom, args, JS('', 'void 0'));
+  return definiteFunctionType(bottom, args, JS('', 'void 0'));
 }
 
 /// Returns the runtime representation of the type of obj.