Fix index register assignment in LoadFieldByIndex for arm, arm64, and mips.

src/arm/lithium-arm.cc

Index: src/arm/lithium-arm.cc
diff --git a/src/arm/lithium-arm.cc b/src/arm/lithium-arm.cc
index 0c10a65c217f7841fa70c5ba780ec84bc633a787..c9201a80708139b6b4c2922c0a09945cd9bdcf92 100644
--- a/src/arm/lithium-arm.cc
+++ b/src/arm/lithium-arm.cc
@@ -2556,7 +2556,7 @@ LInstruction* LChunkBuilder::DoCheckMapValue(HCheckMapValue* instr) {
 
 LInstruction* LChunkBuilder::DoLoadFieldByIndex(HLoadFieldByIndex* instr) {
   LOperand* object = UseRegister(instr->object());
-  LOperand* index = UseRegister(instr->index());
+  LOperand* index = UseTempRegister(instr->index());
   LLoadFieldByIndex* load = new(zone()) LLoadFieldByIndex(object, index);
   LInstruction* result = DefineSameAsFirst(load);
   return AssignPointerMap(result);