[VM/kernel] Remove obsolete workaround when reading dynamic bound from kernel.

If the bound is not specified, CFE will use Object* in an opted-out library or Object? in an opted-in library, and not dynamic as before.
This workaround is therefore not needed anymore, and actually harmful as shown in the regression tests.

Closes #44136
Add regression tests.

Change-Id: I11a96cbebcb592f66f3965e38cb2411200df332b
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/171380
Reviewed-by: Alexander Markov <[email protected]>
Commit-Queue: Régis Crelier <[email protected]>

Author: crelier

runtime/vm/compiler/frontend/kernel_translation_helper.cc

@@ -3338,20 +3338,9 @@ void TypeTranslator::LoadAndSetupTypeParameters(
     TypeParameterHelper helper(helper_);
     helper.ReadUntilExcludingAndSetJustRead(TypeParameterHelper::kBound);
 
-    // TODO(github.com/dart-lang/kernel/issues/42): This should be handled
-    // by the frontend.
     parameter ^= type_parameters.TypeAt(i);
-    const Tag tag = helper_->PeekTag();  // peek ith bound type.
-    if (tag == kDynamicType) {
-      helper_->SkipDartType();  // read ith bound.
-      parameter.set_bound(
-          Type::Handle(Z, nnbd_mode == NNBDMode::kOptedInLib
-                              ? I->object_store()->nullable_object_type()
-                              : I->object_store()->legacy_object_type()));
-    } else {
-      AbstractType& bound = BuildTypeWithoutFinalization();  // read ith bound.
-      parameter.set_bound(bound);
-    }
+    AbstractType& bound = BuildTypeWithoutFinalization();  // read ith bound.
+    parameter.set_bound(bound);
     helper.ReadUntilExcludingAndSetJustRead(TypeParameterHelper::kDefaultType);
     const AbstractType* default_arg = &Object::dynamic_type();
     if (helper_->ReadTag() == kSomething) {

tests/language/regress/regress44136_test.dart

@@ -0,0 +1,12 @@
+// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import "package:expect/expect.dart";
+
+typedef Foo = void Function<X extends dynamic>();
+typedef Bar = void Function<X extends Object?>();
+
+void main() {
+  Expect.notEquals(Foo, Bar);
+}

tests/language_2/regress/regress44136_test.dart

@@ -0,0 +1,12 @@
+// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import "package:expect/expect.dart";
+
+typedef Foo = void Function<X extends dynamic>();
+typedef Bar = void Function<X extends Object>();
+
+void main() {
+  Expect.notEquals(Foo, Bar);
+}