Bug 1393732 - Correct ARM codegen for 32-to-64 sign extend. r=nbp

--HG--
extra : rebase_source : 1366fc2430156e4a1bcecd4b5431af9444d46f8b

js/src/jit/arm/CodeGenerator-arm.cpp

@@ -3104,6 +3104,7 @@ CodeGeneratorARM::visitSignExtendInt64(LSignExtendInt64* lir)
         masm.move16SignExtend(input.low, output.low);
         break;
       case MSignExtendInt64::Word:
+        masm.move32(input.low, output.low);
         break;
     }
     masm.ma_asr(Imm32(31), output.low, output.high);