[turbofan] Remove dead code from SimplifiedLowering.

src/compiler/simplified-lowering.cc

Index: src/compiler/simplified-lowering.cc
diff --git a/src/compiler/simplified-lowering.cc b/src/compiler/simplified-lowering.cc
index 1bf1e4fb3ebbf3916370c596eab327cc6a6839fc..d1f6c8743bbe466d850ca74493daaa6f8b09f425 100644
--- a/src/compiler/simplified-lowering.cc
+++ b/src/compiler/simplified-lowering.cc
@@ -2335,12 +2335,10 @@ class RepresentationSelector {
 };
 
 SimplifiedLowering::SimplifiedLowering(JSGraph* jsgraph, Zone* zone,
-                                       SourcePositionTable* source_positions,
-                                       Flags flags)
+                                       SourcePositionTable* source_positions)
     : jsgraph_(jsgraph),
       zone_(zone),
       type_cache_(TypeCache::Get()),
-      flags_(flags),
       source_positions_(source_positions) {}
 
 void SimplifiedLowering::LowerAllNodes() {