Reapply change to hide VM-only List implementation classes.

runtime/vm/intrinsifier_x64.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 "vm/globals.h"  // Needed here to get TARGET_ARCH_X64.
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/intrinsifier.h"
 
 #include "vm/assembler.h"
@@ skipping 1219 matching lines @@
   __ LoadObject(RAX, bool_true);
   __ ret();
   return true;
 }
 
 
 static intptr_t GetOffsetForField(const char* class_name_p,
                                   const char* field_name_p) {
   const String& class_name = String::Handle(Symbols::New(class_name_p));
   const String& field_name = String::Handle(Symbols::New(field_name_p));
-  const Class& cls = Class::Handle(Library::Handle(
-      Library::CoreImplLibrary()).LookupClass(class_name));
+  const Library& coreimpl_lib = Library::Handle(Library::CoreImplLibrary());
+  const Class& cls =
+      Class::Handle(coreimpl_lib.LookupClassAllowPrivate(class_name));
   ASSERT(!cls.IsNull());
   const Field& field = Field::ZoneHandle(cls.LookupInstanceField(field_name));
   ASSERT(!field.IsNull());
   return field.Offset();
 }
 
-static const char* kFixedSizeArrayIteratorClassName = "FixedSizeArrayIterator";
+
+static const char* kFixedSizeArrayIteratorClassName = "_FixedSizeArrayIterator";
 
 // Class 'FixedSizeArrayIterator':
 //   T next() {
 //     return _array[_pos++];
 //   }
 // Intrinsify: return _array[_pos++];
 // TODO(srdjan): Throw a 'NoMoreElementsException' exception if the iterator
 // has no more elements.
 bool Intrinsifier::FixedSizeArrayIterator_next(Assembler* assembler) {
   Label fall_through;
@@ skipping 124 matching lines @@
   __ LoadObject(RAX, bool_true);
   __ ret();
   return true;
 }
 
 #undef __
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64