Use symbols when looking up fields in a class

runtime/lib/math.cc

 // Copyright (c) 2011, 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 <ctype.h>  // isspace.
 
 #include "vm/bootstrap_natives.h"
 
 #include "vm/exceptions.h"
 #include "vm/native_entry.h"
@@ skipping 61 matching lines @@
       Double, exponent_object, arguments->NativeArgAt(1));
   const double exponent = exponent_object.value();
   return Double::New(pow(operand, exponent));
 }
 
 
 // Returns the typed-data array store in '_Random._state' field.
 static RawTypedData* GetRandomStateArray(const Instance& receiver) {
   const Class& random_class = Class::Handle(receiver.clazz());
   const Field& state_field =
-      Field::Handle(random_class.LookupField(Symbols::_state()));
+      Field::Handle(random_class.LookupFieldAllowPrivate(Symbols::_state()));
   ASSERT(!state_field.IsNull());
   const Instance& state_field_value =
       Instance::Cast(Object::Handle(receiver.GetField(state_field)));
   ASSERT(!state_field_value.IsNull());
   ASSERT(state_field_value.IsTypedData());
   const TypedData& array = TypedData::Cast(state_field_value);
   ASSERT(array.Length() == 2);
   ASSERT(array.ElementType() == kUint32ArrayElement);
   return array.raw();
 }
@@ skipping 121 matching lines @@
     Exceptions::ThrowByType(Exceptions::kUnsupported, args);
   }
   uint64_t result = 0;
   for (intptr_t i = 0; i < n; i++) {
     result = (result << 8) | buffer[i];
   }
   return Integer::New(result);
 }
 
 }  // namespace dart