[es6] Mark tail Call nodes

src/parsing/parser.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/parsing/parser.h"
 
 #include "src/api.h"
 #include "src/ast/ast.h"
 #include "src/ast/ast-expression-visitor.h"
 #include "src/ast/ast-literal-reindexer.h"
@@ skipping 2892 matching lines @@
       // temp === undefined
       Expression* is_undefined = factory()->NewCompareOperation(
           Token::EQ_STRICT, assign,
           factory()->NewUndefinedLiteral(RelocInfo::kNoPosition), pos);
 
       // is_undefined ? this : is_object_conditional
       return_value = factory()->NewConditional(
           is_undefined, ThisExpression(scope_, factory(), pos),
           is_object_conditional, pos);
     }
+
+    return_value->MarkTail();
   }
   ExpectSemicolon(CHECK_OK);
 
   if (is_generator()) {
     Expression* generator = factory()->NewVariableProxy(
         function_state_->generator_object_variable());
     Expression* yield = factory()->NewYield(
         generator, return_value, Yield::kFinal, loc.beg_pos);
     result = factory()->NewExpressionStatement(yield, loc.beg_pos);
   } else {
@@ skipping 3668 matching lines @@
 
 void ParserTraits::QueueDestructuringAssignmentForRewriting(Expression* expr) {
   DCHECK(expr->IsRewritableAssignmentExpression());
   parser_->function_state_->AddDestructuringAssignment(
       Parser::DestructuringAssignment(expr, parser_->scope_));
 }
 
 
 }  // namespace internal
 }  // namespace v8