Use symbols when looking up fields in a class

runtime/vm/object.h

 // 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.
 
 #ifndef VM_OBJECT_H_
 #define VM_OBJECT_H_
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "platform/utils.h"
@@ skipping 1177 matching lines @@
   RawFunction* LookupConstructorAllowPrivate(const String& name) const;
   RawFunction* LookupFactory(const String& name) const;
   RawFunction* LookupFactoryAllowPrivate(const String& name) const;
   RawFunction* LookupFunction(const String& name) const;
   RawFunction* LookupFunctionAllowPrivate(const String& name) const;
   RawFunction* LookupGetterFunction(const String& name) const;
   RawFunction* LookupSetterFunction(const String& name) const;
   RawField* LookupInstanceField(const String& name) const;
   RawField* LookupStaticField(const String& name) const;
   RawField* LookupField(const String& name) const;
+  RawField* LookupFieldAllowPrivate(const String& name) const;
+  RawField* LookupInstanceFieldAllowPrivate(const String& name) const;
+  RawField* LookupStaticFieldAllowPrivate(const String& name) const;
 
   RawLibraryPrefix* LookupLibraryPrefix(const String& name) const;
 
   // Returns an instance of Double or Double::null().
   // 'index' points to either:
   // - constants_list_ position of found element, or
   // - constants_list_ position where new canonical can be inserted.
   RawDouble* LookupCanonicalDouble(Zone* zone,
                                    double value, intptr_t* index) const;
   RawMint* LookupCanonicalMint(Zone* zone,
@@ skipping 7230 matching lines @@
 
 
 RawObject* MegamorphicCache::GetTargetFunction(const Array& array,
                                                intptr_t index) {
   return array.At((index * kEntryLength) + kTargetFunctionIndex);
 }
 
 }  // namespace dart
 
 #endif  // VM_OBJECT_H_