[heap] Use struct Entry to fill inlined promotion queue entries.

src/heap/heap-inl.h

Index: src/heap/heap-inl.h
diff --git a/src/heap/heap-inl.h b/src/heap/heap-inl.h
index 1480da34108c5e49cd992b10de421520f777e0aa..0cfcfe572315e0e1edff4190169764f31c8586cb 100644
--- a/src/heap/heap-inl.h
+++ b/src/heap/heap-inl.h
@@ -25,20 +25,23 @@
 namespace v8 {
 namespace internal {
 
-void PromotionQueue::insert(HeapObject* target, int size) {
+void PromotionQueue::insert(HeapObject* target, intptr_t size) {
   if (emergency_stack_ != NULL) {
     emergency_stack_->Add(Entry(target, size));
     return;
   }
 
-  if ((rear_ - 2) < limit_) {
+  if ((rear_ - kEntrySizeInWords) < limit_) {
     RelocateQueueHead();
     emergency_stack_->Add(Entry(target, size));
     return;
   }
 
-  *(--rear_) = reinterpret_cast<intptr_t>(target);
-  *(--rear_) = size;
+  rear_ -= kEntrySizeInWords;
+  struct Entry* entry = reinterpret_cast<struct Entry*>(rear_);
+  entry->obj_ = target;
+  entry->size_ = size;
+
 // Assert no overflow into live objects.
 #ifdef DEBUG
   SemiSpace::AssertValidRange(target->GetIsolate()->heap()->new_space()->top(),