Consistently make the bounds check for AccessArgumentsAt explicit.

src/arm/lithium-codegen-arm.cc

Index: src/arm/lithium-codegen-arm.cc
diff --git a/src/arm/lithium-codegen-arm.cc b/src/arm/lithium-codegen-arm.cc
index 3da16cdc177169974c816a66aed68a1663e70b87..d5b67a7a1ba65078c8eec836adc8967404dd6f05 100644
--- a/src/arm/lithium-codegen-arm.cc
+++ b/src/arm/lithium-codegen-arm.cc
@@ -2904,14 +2904,9 @@ void LCodeGen::DoAccessArgumentsAt(LAccessArgumentsAt* instr) {
   Register length = ToRegister(instr->length());
   Register index = ToRegister(instr->index());
   Register result = ToRegister(instr->result());
-
-  // Bailout index is not a valid argument index. Use unsigned check to get
-  // negative check for free.
-  __ sub(length, length, index, SetCC);
-  DeoptimizeIf(ls, instr->environment());
-
   // There are two words between the frame pointer and the last argument.
   // Subtracting from length accounts for one of them add one more.
+  __ sub(length, length, index);
   __ add(length, length, Operand(1));
   __ ldr(result, MemOperand(arguments, length, LSL, kPointerSizeLog2));
 }