Refactor delay set to allow more than one marking visitor

runtime/vm/raw_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_RAW_OBJECT_H_
 #define VM_RAW_OBJECT_H_
 
 #include "platform/assert.h"
 #include "vm/atomic.h"
 #include "vm/globals.h"
@@ skipping 1909 matching lines @@
 
   RawObject** from() {
     return reinterpret_cast<RawObject**>(&ptr()->key_);
   }
   RawObject* key_;
   RawObject* value_;
   RawObject** to() {
     return reinterpret_cast<RawObject**>(&ptr()->value_);
   }
 
+  friend class DelaySet;
   friend class GCMarker;
   friend class MarkingVisitor;
   friend class Scavenger;
   friend class ScavengerVisitor;
 };
 
 // MirrorReferences are used by mirrors to hold reflectees that are VM
 // internal objects, such as libraries, classes, functions or types.
 class RawMirrorReference : public RawInstance {
   RAW_HEAP_OBJECT_IMPLEMENTATION(MirrorReference);
@@ skipping 242 matching lines @@
   COMPILE_ASSERT(kExternalTypedDataInt8ArrayCid ==
                  kTypedDataInt8ArrayViewCid + 15);
   COMPILE_ASSERT(kByteBufferCid == kExternalTypedDataInt8ArrayCid + 14);
   COMPILE_ASSERT(kNullCid == kByteBufferCid + 1);
   return (kNullCid - kTypedDataInt8ArrayCid);
 }
 
 }  // namespace dart
 
 #endif  // VM_RAW_OBJECT_H_