Make NoReloadScope thread safe

runtime/vm/atomic.h

Index: runtime/vm/atomic.h
diff --git a/runtime/vm/atomic.h b/runtime/vm/atomic.h
index d6a833bb313b61e5fe8a3c548e89eeef1ba02cfc..e16eee18a5213234cdd220709c8637a93529ad5d 100644
--- a/runtime/vm/atomic.h
+++ b/runtime/vm/atomic.h
@@ -20,6 +20,7 @@ class AtomicOperations : public AllStatic {
   // NOTE: Not to be used for any atomic operations involving memory locations
   // that are accessed by generated code.
   static uintptr_t FetchAndIncrement(uintptr_t* p);
+  static intptr_t FetchAndIncrement(intptr_t* p);
 
   // Atomically increment the value at p by 'value'.
   //
@@ -34,6 +35,7 @@ class AtomicOperations : public AllStatic {
   // NOTE: Not to be used for any atomic operations involving memory locations
   // that are accessed by generated code.
   static uintptr_t FetchAndDecrement(uintptr_t* p);
+  static intptr_t FetchAndDecrement(intptr_t* p);
 
   // Atomically decrement the value at p by 'value'.
   //