Fix the GC branch so it compiles and runs on 64 bit.

src/x64/macro-assembler-x64.h

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 41 matching lines @@
 static const Register kRootRegister = { 13 };         // r13 (callee save).
 // Value of smi in kSmiConstantRegister.
 static const int kSmiConstantRegisterValue = 1;
 // Actual value of root register is offset from the root array's start
 // to take advantage of negitive 8-bit displacement values.
 static const int kRootRegisterBias = 128;
 
 // Convenience for platform-independent signatures.
 typedef Operand MemOperand;
 
+enum EmitRememberedSet { EMIT_REMEMBERED_SET, OMIT_REMEMBERED_SET };
+enum SmiCheck { INLINE_SMI_CHECK, OMIT_SMI_CHECK };
+
+bool Aliasing(Register r1, Register r2, Register r3, Register r4);
+
 // Forward declaration.
 class JumpTarget;
 
 struct SmiIndex {
   SmiIndex(Register index_register, ScaleFactor scale)
       : reg(index_register),
         scale(scale) {}
   Register reg;
   ScaleFactor scale;
 };
@@ skipping 1925 matching lines @@
       Jump(adaptor, RelocInfo::CODE_TARGET);
     }
     bind(&invoke);
   }
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_X64_MACRO_ASSEMBLER_X64_H_