MIPS: Remove extranous holder load in some prototype-chain checking cases

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 652c7cad079c0a21122c3fda060d9eb551abdd19..7a2975a3695df277f9c721127e3ae69f55ef1941 100644
--- a/src/mips/lithium-mips.cc
+++ b/src/mips/lithium-mips.cc
@@ -1807,7 +1807,7 @@ LInstruction* LChunkBuilder::DoCheckPrototypeMaps(HCheckPrototypeMaps* instr) {
   LUnallocated* temp1 = TempRegister();
   LOperand* temp2 = TempRegister();
   LCheckPrototypeMaps* result = new(zone()) LCheckPrototypeMaps(temp1, temp2);
-  return AssignEnvironment(Define(result, temp1));
+  return AssignEnvironment(result);
 }