Use memcpy for Atomic::LoadRelaxed.

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 43 matching lines @@
   return static_cast<uword>(
       InterlockedCompareExchange(reinterpret_cast<LONG*>(ptr),
                                  static_cast<LONG>(new_value),
                                  static_cast<LONG>(old_value)));
 #else
   UNIMPLEMENTED();
 #endif
 }
 #endif  // !defined(USING_SIMULATOR)
 
-
-inline uword AtomicOperations::LoadRelaxed(uword* ptr) {
-  // TODO(koda): Consider using C++11 <atomic> to avoid the barrier on more
-  // compilers/platforms.
-  return FetchAndAdd(reinterpret_cast<intptr_t*>(ptr), 0);
-}
-
 }  // namespace dart
 
 #endif  // VM_ATOMIC_WIN_H_