Disable ES6 tail call elimination for native functions.

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-rewriter.h"
 #include "src/ast/ast-expression-visitor.h"
@@ skipping 765 matching lines @@
       cached_parse_data_(NULL),
       total_preparse_skipped_(0),
       pre_parse_timer_(NULL),
       parsing_on_main_thread_(true) {
   // Even though we were passed ParseInfo, we should not store it in
   // Parser - this makes sure that Isolate is not accidentally accessed via
   // ParseInfo during background parsing.
   DCHECK(!info->script().is_null() || info->source_stream() != NULL);
   set_allow_lazy(info->allow_lazy_parsing());
   set_allow_natives(FLAG_allow_natives_syntax || info->is_native());
+  set_allow_tailcalls(FLAG_harmony_tailcalls && !info->is_native());
   set_allow_harmony_sloppy(FLAG_harmony_sloppy);
   set_allow_harmony_sloppy_function(FLAG_harmony_sloppy_function);
   set_allow_harmony_sloppy_let(FLAG_harmony_sloppy_let);
   set_allow_legacy_const(FLAG_legacy_const);
   set_allow_harmony_do_expressions(FLAG_harmony_do_expressions);
   set_allow_harmony_function_name(FLAG_harmony_function_name);
   set_allow_harmony_function_sent(FLAG_harmony_function_sent);
   set_allow_harmony_restrictive_declarations(
       FLAG_harmony_restrictive_declarations);
   set_allow_harmony_exponentiation_operator(
@@ skipping 1877 matching lines @@
           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);
     }
 
     // ES6 14.6.1 Static Semantics: IsInTailPosition
-    if (FLAG_harmony_tailcalls && !is_sloppy(language_mode())) {
+    if (allow_tailcalls() && !is_sloppy(language_mode())) {
       function_state_->AddExpressionInTailPosition(return_value);
     }
   }
   ExpectSemicolon(CHECK_OK);
 
   if (is_generator()) {
     return_value = BuildIteratorResult(return_value, true);
   }
 
   result = factory()->NewReturnStatement(return_value, loc.beg_pos);
@@ skipping 4182 matching lines @@
                         try_block, target);
     final_loop = target;
   }
 
   return final_loop;
 }
 
 
 }  // namespace internal
 }  // namespace v8