[heap] Make AlwaysAllocateScope thread-safe.

src/heap/heap-inl.h

 // Copyright 2012 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_HEAP_HEAP_INL_H_
 #define V8_HEAP_HEAP_INL_H_
 
 #include <cmath>
 
 #include "src/base/platform/platform.h"
@@ skipping 731 matching lines @@
 
 
 void Heap::SetSetterStubDeoptPCOffset(int pc_offset) {
   DCHECK(setter_stub_deopt_pc_offset() == Smi::FromInt(0));
   set_setter_stub_deopt_pc_offset(Smi::FromInt(pc_offset));
 }
 
 
 AlwaysAllocateScope::AlwaysAllocateScope(Isolate* isolate)
     : heap_(isolate->heap()), daf_(isolate) {
-  heap_->always_allocate_scope_depth_++;
+  heap_->always_allocate_scope_count_.Increment(1);
 }
 
 
 AlwaysAllocateScope::~AlwaysAllocateScope() {
-  heap_->always_allocate_scope_depth_--;
+  heap_->always_allocate_scope_count_.Increment(-1);
 }
 
 
 GCCallbacksScope::GCCallbacksScope(Heap* heap) : heap_(heap) {
   heap_->gc_callbacks_depth_++;
 }
 
 
 GCCallbacksScope::~GCCallbacksScope() { heap_->gc_callbacks_depth_--; }
 
@@ skipping 16 matching lines @@
 
 void VerifySmisVisitor::VisitPointers(Object** start, Object** end) {
   for (Object** current = start; current < end; current++) {
     CHECK((*current)->IsSmi());
   }
 }
 }
 }  // namespace v8::internal
 
 #endif  // V8_HEAP_HEAP_INL_H_