[crankshaft] Remove the useless HCallStub instruction.

src/crankshaft/ia32/lithium-ia32.cc

Index: src/crankshaft/ia32/lithium-ia32.cc
diff --git a/src/crankshaft/ia32/lithium-ia32.cc b/src/crankshaft/ia32/lithium-ia32.cc
index 130ac852d33bfe6490b6c62de717ebe8a314c82d..3f97040234c34b2a9e9ad698de0a5b99eca60a49 100644
--- a/src/crankshaft/ia32/lithium-ia32.cc
+++ b/src/crankshaft/ia32/lithium-ia32.cc
@@ -2517,13 +2517,6 @@ LInstruction* LChunkBuilder::DoUnknownOSRValue(HUnknownOSRValue* instr) {
 }
 
 
-LInstruction* LChunkBuilder::DoCallStub(HCallStub* instr) {
-  LOperand* context = UseFixed(instr->context(), esi);
-  LCallStub* result = new(zone()) LCallStub(context);
-  return MarkAsCall(DefineFixed(result, eax), instr);
-}
-
-
 LInstruction* LChunkBuilder::DoArgumentsObject(HArgumentsObject* instr) {
   // There are no real uses of the arguments object.
   // arguments.length and element access are supported directly on