MIPS: Remove the first_right_arg hack for HMod.

src/mips/lithium-mips.cc

Index: src/mips/lithium-mips.cc
diff --git a/src/mips/lithium-mips.cc b/src/mips/lithium-mips.cc
index fb816273547058d7e6a829e5e0dab64406df8429..abdc3e6da14ea1e553b4a9e094811d5b93c41910 100644
--- a/src/mips/lithium-mips.cc
+++ b/src/mips/lithium-mips.cc
@@ -1460,10 +1460,6 @@ LInstruction* LChunkBuilder::DoMod(HMod* instr) {
               instr->CheckFlag(HValue::kBailoutOnMinusZero))
           ? AssignEnvironment(result)
           : result;
-    } else if (instr->fixed_right_arg().has_value) {
-      LModI* mod = new(zone()) LModI(UseRegisterAtStart(left),
-                                     UseRegisterAtStart(right));
-      return AssignEnvironment(DefineAsRegister(mod));
     } else {
       LModI* mod = new(zone()) LModI(UseRegister(left),
                                      UseRegister(right),