expose AssertNoAllocation to api

src/heap.h

Index: src/heap.h
diff --git a/src/heap.h b/src/heap.h
index 7722079e55049ef94f572b45d1593ec16787f6ae..e97568daf34eb5288edbad1a4de28850e8aabab4 100644
--- a/src/heap.h
+++ b/src/heap.h
@@ -2691,6 +2691,15 @@ class DescriptorLookupCache {
 // { AssertNoAllocation nogc;
 //   ...
 // }
+
+#ifdef DEBUG
+typedef uint8_t AllocationScopeData;
+inline AllocationScopeData EnterAllocationScope(Isolate* isolate,
+                                                bool allow_allocation);
+inline void ExitAllocationScope(Isolate* isolate, AllocationScopeData);
+#endif
+
+
 class AssertNoAllocation {
  public:
   inline AssertNoAllocation();
@@ -2698,8 +2707,7 @@ class AssertNoAllocation {
 
 #ifdef DEBUG
  private:
-  bool old_state_;
-  bool active_;
+  AllocationScopeData data_;
 #endif
 };
 
@@ -2711,8 +2719,7 @@ class DisableAssertNoAllocation {
 
 #ifdef DEBUG
  private:
-  bool old_state_;
-  bool active_;
+  AllocationScopeData data_;
 #endif
 };