Do not hide membership of implementation classes in dart:core.

runtime/lib/mirrors.cc

 // Copyright (c) 2012, 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.
 
 #include "lib/invocation_mirror.h"
 #include "vm/bootstrap_natives.h"
 #include "vm/class_finalizer.h"
 #include "vm/compiler.h"
 #include "vm/dart_entry.h"
 #include "vm/exceptions.h"
@@ skipping 1099 matching lines @@
 
   Object& entry = Object::Handle();
   DictionaryIterator entries(library);
 
   AbstractType& type = AbstractType::Handle();
 
   while (entries.HasNext()) {
     entry = entries.GetNext();
     if (entry.IsClass()) {
       const Class& klass = Class::Cast(entry);
-      // We filter out implementation classes like Smi, Mint, Bignum,
-      // OneByteString; function signature classes; and dynamic.
+      // We filter out function signature classes and dynamic.
+      // TODO(12478): Should not need to filter out dynamic.
       if (!klass.IsCanonicalSignatureClass() &&
-          !klass.IsDynamicClass() &&
-          !RawObject::IsImplementationClassId(klass.id())) {
+          !klass.IsDynamicClass()) {
         type = klass.RareType();
         member_mirror = CreateClassMirror(klass,
                                           type,
                                           Bool::True(),  // is_declaration
                                           owner_mirror);
         member_mirrors.Add(member_mirror);
       }
     } else if (entry.IsField()) {
       const Field& field = Field::Cast(entry);
       member_mirror = CreateVariableMirror(field, owner_mirror);
@@ skipping 720 matching lines @@
 }
 
 
 DEFINE_NATIVE_ENTRY(VariableMirror_type, 1) {
   GET_NON_NULL_NATIVE_ARGUMENT(MirrorReference, ref, arguments->NativeArgAt(0));
   const Field& field = Field::Handle(ref.GetFieldReferent());
   return field.type();
 }
 
 }  // namespace dart