[compiler] Delete unused variable.

BUG=

Review-Url: https://codereview.chromium.org/2257393002
Cr-Commit-Position: refs/heads/master@{#38743}

src/compiler/loop-variable-optimizer.cc

@@ -149,8 +149,7 @@ class LoopVariableOptimizer::VariableLimits : public ZoneObject {
 };
 
 void InductionVariable::AddUpperBound(Node* bound,
-                                      InductionVariable::ConstraintKind kind,
-                                      Zone* graph_zone) {
+                                      InductionVariable::ConstraintKind kind) {
   if (FLAG_trace_turbo_loop) {
     OFStream os(stdout);
     os << "New upper bound for " << phi()->id() << " (loop "
@@ -161,8 +160,7 @@ void InductionVariable::AddUpperBound(Node* bound,
 }
 
 void InductionVariable::AddLowerBound(Node* bound,
-                                      InductionVariable::ConstraintKind kind,
-                                      Zone* graph_zone) {
+                                      InductionVariable::ConstraintKind kind) {
   if (FLAG_trace_turbo_loop) {
     OFStream os(stdout);
     os << "New lower bound for " << phi()->id() << " (loop "
@@ -183,16 +181,14 @@ void LoopVariableOptimizer::VisitBackedge(Node* from, Node* loop) {
         NodeProperties::GetControlInput(constraint->left()) == loop) {
       auto var = induction_vars_.find(constraint->left()->id());
       if (var != induction_vars_.end()) {
-        var->second->AddUpperBound(constraint->right(), constraint->kind(),
-                                   graph()->zone());
+        var->second->AddUpperBound(constraint->right(), constraint->kind());
       }
     }
     if (constraint->right()->opcode() == IrOpcode::kPhi &&
         NodeProperties::GetControlInput(constraint->right()) == loop) {
       auto var = induction_vars_.find(constraint->right()->id());
       if (var != induction_vars_.end()) {
-        var->second->AddUpperBound(constraint->left(), constraint->kind(),
-                                   graph()->zone());
+        var->second->AddUpperBound(constraint->left(), constraint->kind());
       }
     }
   }

src/compiler/loop-variable-optimizer.h

@@ -45,8 +45,8 @@ class InductionVariable : public ZoneObject {
         lower_bounds_(zone),
         upper_bounds_(zone) {}
 
-  void AddUpperBound(Node* bound, ConstraintKind kind, Zone* graph_zone);
-  void AddLowerBound(Node* bound, ConstraintKind kind, Zone* graph_zone);
+  void AddUpperBound(Node* bound, ConstraintKind kind);
+  void AddLowerBound(Node* bound, ConstraintKind kind);
 
   Node* phi_;
   Node* arith_;