Make NoReloadScope thread safe

runtime/vm/atomic_win.h

Index: runtime/vm/atomic_win.h
diff --git a/runtime/vm/atomic_win.h b/runtime/vm/atomic_win.h
index 38ec10a1f8996841078d0dec585ed38f8fe84601..2f8ee20b5817e77e7869ba3dccfa857e21bdc441 100644
--- a/runtime/vm/atomic_win.h
+++ b/runtime/vm/atomic_win.h
@@ -28,6 +28,19 @@ inline uintptr_t AtomicOperations::FetchAndIncrement(uintptr_t* p) {
 }
 
 
+inline intptr_t AtomicOperations::FetchAndIncrement(intptr_t* p) {
+#if defined(HOST_ARCH_X64)
+  return static_cast<intptr_t>(
+      InterlockedIncrement64(reinterpret_cast<LONGLONG*>(p))) - 1;
+#elif defined(HOST_ARCH_IA32)
+  return static_cast<intptr_t>(
+      InterlockedIncrement(reinterpret_cast<LONG*>(p))) - 1;
+#else
+#error Unsupported host architecture.
+#endif
+}
+
+
 inline void AtomicOperations::IncrementBy(intptr_t* p, intptr_t value) {
 #if defined(HOST_ARCH_X64)
   InterlockedExchangeAdd64(reinterpret_cast<LONGLONG*>(p),
@@ -64,6 +77,19 @@ inline uintptr_t AtomicOperations::FetchAndDecrement(uintptr_t* p) {
 }
 
 
+inline intptr_t AtomicOperations::FetchAndDecrement(intptr_t* p) {
+#if defined(HOST_ARCH_X64)
+  return static_cast<intptr_t>(
+      InterlockedDecrement64(reinterpret_cast<LONGLONG*>(p))) + 1;
+#elif defined(HOST_ARCH_IA32)
+  return static_cast<intptr_t>(
+      InterlockedDecrement(reinterpret_cast<LONG*>(p))) + 1;
+#else
+#error Unsupported host architecture.
+#endif
+}
+
+
 inline void AtomicOperations::DecrementBy(intptr_t* p, intptr_t value) {
 #if defined(HOST_ARCH_X64)
   InterlockedExchangeAdd64(reinterpret_cast<LONGLONG*>(p),