Remove the first_right_arg hack for HMod.

src/x64/lithium-x64.cc

 // Copyright 2012 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 1451 matching lines @@
     if (instr->HasPowerOf2Divisor()) {
       ASSERT(!right->CanBeZero());
       LModI* mod = new(zone()) LModI(UseRegisterAtStart(left),
                                      UseOrConstant(right),
                                      NULL);
       LInstruction* result = DefineSameAsFirst(mod);
       return (left->CanBeNegative() &&
               instr->CheckFlag(HValue::kBailoutOnMinusZero))
           ? AssignEnvironment(result)
           : result;
-    } else if (instr->fixed_right_arg().has_value) {
-      LModI* mod = new(zone()) LModI(UseRegister(left),
-                                     UseRegisterAtStart(right),
-                                     NULL);
-      return AssignEnvironment(DefineSameAsFirst(mod));
     } else {
       // The temporary operand is necessary to ensure that right is not
       // allocated into edx.
       LModI* mod = new(zone()) LModI(UseFixed(left, rax),
                                      UseRegister(right),
                                      FixedTemp(rdx));
       LInstruction* result = DefineFixed(mod, rdx);
       return (right->CanBeZero() ||
               (left->RangeCanInclude(kMinInt) &&
                right->RangeCanInclude(-1) &&
@@ skipping 1139 matching lines @@
 LInstruction* LChunkBuilder::DoLoadFieldByIndex(HLoadFieldByIndex* instr) {
   LOperand* object = UseRegister(instr->object());
   LOperand* index = UseTempRegister(instr->index());
   return DefineSameAsFirst(new(zone()) LLoadFieldByIndex(object, index));
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64