[turbofan] Remove dead {is_liveness_analysis_enabled}.

src/compiler/bytecode-graph-builder.h

Index: src/compiler/bytecode-graph-builder.h
diff --git a/src/compiler/bytecode-graph-builder.h b/src/compiler/bytecode-graph-builder.h
index 0fffc77b70e945527a5a8a90521398c5e9a56232..1f613278dbd19c000bc82f7332d14babc2f34c97 100644
--- a/src/compiler/bytecode-graph-builder.h
+++ b/src/compiler/bytecode-graph-builder.h
@@ -261,10 +261,6 @@ class BytecodeGraphBuilder {
     bytecode_analysis_ = bytecode_analysis;
   }
 
-  bool IsLivenessAnalysisEnabled() const {
-    return this->is_liveness_analysis_enabled_;
-  }
-
 #define DECLARE_VISIT_BYTECODE(name, ...) void Visit##name();
   BYTECODE_LIST(DECLARE_VISIT_BYTECODE)
 #undef DECLARE_VISIT_BYTECODE
@@ -303,8 +299,6 @@ class BytecodeGraphBuilder {
   // Control nodes that exit the function body.
   ZoneVector<Node*> exit_controls_;
 
-  bool const is_liveness_analysis_enabled_;
-
   StateValuesCache state_values_cache_;
 
   // The source position table, to be populated.