[crankshaft] Support ES6 tail call elimination.

src/ast/ast-numbering.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/ast/ast-numbering.h"
 
 #include "src/ast/ast.h"
 #include "src/ast/scopes.h"
 
 namespace v8 {
@@ skipping 486 matching lines @@
   for (int i = 0; i < node->values()->length(); i++) {
     Visit(node->values()->at(i));
   }
   node->BuildConstantElements(isolate_);
   ReserveFeedbackSlots(node);
 }
 
 
 void AstNumberingVisitor::VisitCall(Call* node) {
   IncrementNodeCount();
-  if (node->tail_call_mode() == TailCallMode::kAllow) {
-    DisableOptimization(kTailCall);
-  }
   ReserveFeedbackSlots(node);
   node->set_base_id(ReserveIdRange(Call::num_ids()));
   Visit(node->expression());
   VisitArguments(node->arguments());
 }
 
 
 void AstNumberingVisitor::VisitCallNew(CallNew* node) {
   IncrementNodeCount();
   ReserveFeedbackSlots(node);
@@ skipping 75 matching lines @@
 }
 
 
 bool AstNumbering::Renumber(Isolate* isolate, Zone* zone,
                             FunctionLiteral* function) {
   AstNumberingVisitor visitor(isolate, zone);
   return visitor.Renumber(function);
 }
 }  // namespace internal
 }  // namespace v8