Disable x64 disassembler under win32.

runtime/vm/assembler_macros_x64.h

Index: runtime/vm/assembler_macros_x64.h
===================================================================
--- runtime/vm/assembler_macros_x64.h	(revision 0)
+++ runtime/vm/assembler_macros_x64.h	(revision 0)
@@ -0,0 +1,40 @@
+// Copyright (c) 2011, 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.
+// The class 'AssemblerMacros' contains assembler instruction groups that
+// are used in Dart.
+
+#ifndef VM_ASSEMBLER_MACROS_X64_H_
+#define VM_ASSEMBLER_MACROS_X64_H_
+
+#ifndef VM_ASSEMBLER_MACROS_H_
+#error Do not include assembler_macros_x64.h directly; use assembler_macros.h.
+#endif
+
+#include "vm/allocation.h"
+#include "vm/constants_x64.h"
+
+namespace dart {
+
+// Forward declarations.
+class Assembler;
+class Class;
+class Label;
+
+class AssemblerMacros : public AllStatic {
+ public:
+  // Inlined allocation of an instance of class 'cls', code has no runtime
+  // calls. Jump to 'failure' if the instance cannot be allocated here.
+  // Class must be loaded in 'class_reg'. Allocated instance is returned
+  // in 'instance_reg'. Only the class field of the object is initialized.
+  // 'class_reg' and 'instance_reg' may not be the same register.
+  static void TryAllocate(Assembler* assembler,
+                          const Class& cls,
+                          Register class_reg,
+                          Label* failure,
+                          Register instance_reg);
+};
+
+}  // namespace dart.
+
+#endif  // VM_ASSEMBLER_MACROS_X64_H_