Fix clang build by giving a name to the enum.

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 3738 matching lines @@
   //   - usmi   0000 [used only on 32bit platforms]
   //   - smi    0001
   //   - uint31 0010
   //   - int32  0011
   //   - uint32 0100
   //   - int33  x1x1
   //   - int64  1xxx
   //
   // DecodeRangeFeedbackAt() helper maps these states into the RangeFeedback
   // enumeration.
-  enum {
+  enum RangeFeedbackBits {
     kSignedRangeBit = 1 << 0,
     kInt32RangeBit = 1 << 1,
     kUint32RangeBit = 1 << 2,
     kInt64RangeBit = 1 << 3,
     kBitsPerRangeFeedback = 4,
     kRangeFeedbackMask = (1 << kBitsPerRangeFeedback) - 1
   };
 
   static bool IsValidRangeFeedbackIndex(intptr_t index) {
     return (0 <= index) && (index < 3);
@@ skipping 3898 matching lines @@
 
 
 RawObject* MegamorphicCache::GetTargetFunction(const Array& array,
                                                intptr_t index) {
   return array.At((index * kEntryLength) + kTargetFunctionIndex);
 }
 
 }  // namespace dart
 
 #endif  // VM_OBJECT_H_