Do not add smis to the store buffer when cloning objects.

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/globals.h"
 #include "vm/token.h"
@@ skipping 235 matching lines @@
   class ClassIdTag : public BitField<intptr_t,
                                      kClassIdTagBit,
                                      kClassIdTagSize> {};  // NOLINT
 
   bool IsHeapObject() const {
     uword value = reinterpret_cast<uword>(this);
     return (value & kSmiTagMask) == kHeapObjectTag;
   }
 
   bool IsNewObject() const {
+    ASSERT(IsHeapObject());
     uword addr = reinterpret_cast<uword>(this);
     return (addr & kNewObjectAlignmentOffset) == kNewObjectAlignmentOffset;
   }
   bool IsOldObject() const {
+    ASSERT(IsHeapObject());
     uword addr = reinterpret_cast<uword>(this);
     return (addr & kNewObjectAlignmentOffset) == kOldObjectAlignmentOffset;
   }
   bool IsVMHeapObject() const;
 
   // Support for GC marking bit.
   bool IsMarked() const {
     return MarkBit::decode(ptr()->tags_);
   }
   void SetMarkBit() {
@@ skipping 1435 matching lines @@
          kExternalUint64ArrayCid == kExternalInt8ArrayCid + 8 &&
          kExternalFloat32ArrayCid == kExternalInt8ArrayCid + 9 &&
          kExternalFloat64ArrayCid == kExternalInt8ArrayCid + 10 &&
          kStacktraceCid == kExternalInt8ArrayCid + 11);
   return (index >= kExternalInt8ArrayCid && index <= kExternalFloat64ArrayCid);
 }
 
 }  // namespace dart
 
 #endif  // VM_RAW_OBJECT_H_