Add a CompareAndSwapUint32 variant to AtomicOperations so that it is possible to a CAS of a 32 bit …

runtime/vm/atomic_win.h

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_ATOMIC_WIN_H_
 #define VM_ATOMIC_WIN_H_
 
 #if !defined VM_ATOMIC_H_
 #error Do not include atomic_win.h directly. Use atomic.h instead.
 #endif
@@ skipping 41 matching lines @@
                                    static_cast<LONGLONG>(old_value)));
 #elif defined(HOST_ARCH_IA32)
   return static_cast<uword>(
       InterlockedCompareExchange(reinterpret_cast<LONG*>(ptr),
                                  static_cast<LONG>(new_value),
                                  static_cast<LONG>(old_value)));
 #else
 #error Unsupported host architecture.
 #endif
 }
+inline uint32_t AtomicOperations::CompareAndSwapUint32(uint32_t* ptr,
+                                                       uint32_t old_value,
+                                                       uint32_t new_value) {
+#if (defined(HOST_ARCH_X64) || defined(HOST_ARCH_IA32))
+  return static_cast<uint32_t>(
+      InterlockedCompareExchange(reinterpret_cast<LONG*>(ptr),
+                                 static_cast<LONG>(new_value),
+                                 static_cast<LONG>(old_value)));
+#else
+#error Unsupported host architecture.
+#endif
+}
 #endif  // !defined(USING_SIMULATOR)
 
 }  // namespace dart
 
 #endif  // VM_ATOMIC_WIN_H_