Revert of Remove register index/code indirection

src/ia32/macro-assembler-ia32.h

Index: src/ia32/macro-assembler-ia32.h
diff --git a/src/ia32/macro-assembler-ia32.h b/src/ia32/macro-assembler-ia32.h
index d2f04317f2acf6f4eb944827bd0595da2a58cf8b..2a2338dc07f20b3cca39bfdab6531baa3d64db7d 100644
--- a/src/ia32/macro-assembler-ia32.h
+++ b/src/ia32/macro-assembler-ia32.h
@@ -14,17 +14,17 @@
 namespace internal {
 
 // Give alias names to registers for calling conventions.
-const Register kReturnRegister0 = {Register::kCode_eax};
-const Register kReturnRegister1 = {Register::kCode_edx};
-const Register kJSFunctionRegister = {Register::kCode_edi};
-const Register kContextRegister = {Register::kCode_esi};
-const Register kInterpreterAccumulatorRegister = {Register::kCode_eax};
-const Register kInterpreterRegisterFileRegister = {Register::kCode_edx};
-const Register kInterpreterBytecodeOffsetRegister = {Register::kCode_ecx};
-const Register kInterpreterBytecodeArrayRegister = {Register::kCode_edi};
-const Register kInterpreterDispatchTableRegister = {Register::kCode_ebx};
-const Register kRuntimeCallFunctionRegister = {Register::kCode_ebx};
-const Register kRuntimeCallArgCountRegister = {Register::kCode_eax};
+const Register kReturnRegister0 = {kRegister_eax_Code};
+const Register kReturnRegister1 = {kRegister_edx_Code};
+const Register kJSFunctionRegister = {kRegister_edi_Code};
+const Register kContextRegister = {kRegister_esi_Code};
+const Register kInterpreterAccumulatorRegister = {kRegister_eax_Code};
+const Register kInterpreterRegisterFileRegister = {kRegister_edx_Code};
+const Register kInterpreterBytecodeOffsetRegister = {kRegister_ecx_Code};
+const Register kInterpreterBytecodeArrayRegister = {kRegister_edi_Code};
+const Register kInterpreterDispatchTableRegister = {kRegister_ebx_Code};
+const Register kRuntimeCallFunctionRegister = {kRegister_ebx_Code};
+const Register kRuntimeCallArgCountRegister = {kRegister_eax_Code};
 
 // Spill slots used by interpreter dispatch calling convention.
 const int kInterpreterContextSpillSlot = -1;