[heap] Prevent direct access to StoreBuffer.

src/heap/store-buffer-inl.h

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_STORE_BUFFER_INL_H_
 #define V8_STORE_BUFFER_INL_H_
 
 #include "src/heap/heap.h"
 #include "src/heap/spaces-inl.h"
 #include "src/heap/store-buffer.h"
 
 namespace v8 {
 namespace internal {
 
-Address StoreBuffer::TopAddress() {
-  return reinterpret_cast<Address>(heap_->store_buffer_top_address());
-}
-
-
 void StoreBuffer::Mark(Address addr) {
   DCHECK(!heap_->code_space()->Contains(addr));
   Address* top = reinterpret_cast<Address*>(heap_->store_buffer_top());
   *top++ = addr;
-  heap_->public_set_store_buffer_top(top);
+  heap_->set_store_buffer_top(reinterpret_cast<Smi*>(top));
   if ((reinterpret_cast<uintptr_t>(top) & kStoreBufferOverflowBit) != 0) {
     DCHECK(top == limit_);
     Compact();
   } else {
     DCHECK(top < limit_);
   }
 }
 
 
 void StoreBuffer::EnterDirectlyIntoStoreBuffer(Address addr) {
   if (store_buffer_rebuilding_enabled_) {
     SLOW_DCHECK(!heap_->code_space()->Contains(addr) &&
                 !heap_->new_space()->Contains(addr));
     Address* top = old_top_;
     *top++ = addr;
     old_top_ = top;
     old_buffer_is_sorted_ = false;
     old_buffer_is_filtered_ = false;
     if (top >= old_limit_) {
       DCHECK(callback_ != NULL);
       (*callback_)(heap_, MemoryChunk::FromAnyPointerAddress(heap_, addr),
                    kStoreBufferFullEvent);
     }
   }
 }
 }
 }  // namespace v8::internal
 
 #endif  // V8_STORE_BUFFER_INL_H_