MIPS: Fix AccessArgumentsAt on ARM. Use register for index.

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 9a99d2487885f7c8973a721fe630827f387d9fb9..f0ffda409b2ade83e6d0d30c0431e0677d95ece7 100644
--- a/src/mips/lithium-mips.cc
+++ b/src/mips/lithium-mips.cc
@@ -2358,7 +2358,7 @@ LInstruction* LChunkBuilder::DoAccessArgumentsAt(HAccessArgumentsAt* instr) {
     index = UseOrConstant(instr->index());
   } else {
     length = UseTempRegister(instr->length());
-    index = Use(instr->index());
+    index = UseRegisterAtStart(instr->index());
   }
   return DefineAsRegister(new(zone()) LAccessArgumentsAt(args, length, index));
 }