Fix getField/setField optimization for private members.

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 1293 matching lines @@
   GET_NON_NULL_NATIVE_ARGUMENT(String, expression, arguments->NativeArgAt(0));
   GET_NATIVE_ARGUMENT(String, private_key, arguments->NativeArgAt(1));
 
   const GrowableObjectArray& libraries =
       GrowableObjectArray::Handle(isolate->object_store()->libraries());
   const int num_libraries = libraries.Length();
   Library& each_library = Library::Handle();
   Library& ctxt_library = Library::Handle();
   String& library_key = String::Handle();
 
-  if (library_key.IsNull()) {
+  if (private_key.IsNull()) {
     ctxt_library = Library::CoreLibrary();
   } else {
     for (int i = 0; i < num_libraries; i++) {
       each_library ^= libraries.At(i);
       library_key = each_library.private_key();
       if (library_key.Equals(private_key)) {
         ctxt_library = each_library.raw();
         break;
       }
     }
@@ skipping 792 matching lines @@
 }
 
 DEFINE_NATIVE_ENTRY(TypeMirror_moreSpecificTest, 2) {
   GET_NON_NULL_NATIVE_ARGUMENT(AbstractType, a, arguments->NativeArgAt(0));
   GET_NON_NULL_NATIVE_ARGUMENT(AbstractType, b, arguments->NativeArgAt(1));
   return Bool::Get(a.IsMoreSpecificThan(b, NULL)).raw();
 }
 
 
 }  // namespace dart