Fixing compile warnings for newer GCC versions due to unused variables.

src/ia32/lithium-codegen-ia32.cc

Index: src/ia32/lithium-codegen-ia32.cc
diff --git a/src/ia32/lithium-codegen-ia32.cc b/src/ia32/lithium-codegen-ia32.cc
index 7211ba49a721906b2fbd87d3e611390d4cbae331..982eddb7eda427af6dda4bbcd635c89e942b6055 100644
--- a/src/ia32/lithium-codegen-ia32.cc
+++ b/src/ia32/lithium-codegen-ia32.cc
@@ -2232,7 +2232,6 @@ void LCodeGen::DoLoadKeyedFastElement(LLoadKeyedFastElement* instr) {
 
 void LCodeGen::DoLoadKeyedFastDoubleElement(
     LLoadKeyedFastDoubleElement* instr) {
-  Register elements = ToRegister(instr->elements());
   XMMRegister result = ToDoubleRegister(instr->result());
 
   if (instr->hydrogen()->RequiresHoleCheck()) {
@@ -3097,8 +3096,6 @@ void LCodeGen::DoStoreKeyedFastElement(LStoreKeyedFastElement* instr) {
 void LCodeGen::DoStoreKeyedFastDoubleElement(
     LStoreKeyedFastDoubleElement* instr) {
   XMMRegister value = ToDoubleRegister(instr->value());
-  Register elements = ToRegister(instr->elements());
-  Register key = instr->key()->IsRegister() ? ToRegister(instr->key()) : no_reg;
   Label have_value;
 
   __ ucomisd(value, value);