[es6] Add a flag to the Isolate that defines whether ES2015 tail call elimination is enabled or not.

src/isolate.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/isolate.h"
 
 #include <stdlib.h>
 
 #include <fstream>  // NOLINT(readability/streams)
 #include <sstream>
@@ skipping 1808 matching lines @@
       has_installed_extensions_(false),
       regexp_stack_(NULL),
       date_cache_(NULL),
       call_descriptor_data_(NULL),
       // TODO(bmeurer) Initialized lazily because it depends on flags; can
       // be fixed once the default isolate cleanup is done.
       random_number_generator_(NULL),
       serializer_enabled_(enable_serializer),
       has_fatal_error_(false),
       initialized_from_snapshot_(false),
+      is_tail_call_elimination_enabled_(true),
       cpu_profiler_(NULL),
       heap_profiler_(NULL),
       function_entry_hook_(NULL),
       deferred_handles_head_(NULL),
       optimizing_compile_dispatcher_(NULL),
       stress_deopt_count_(0),
       virtual_handler_register_(NULL),
       virtual_slot_register_(NULL),
       next_optimization_id_(0),
       js_calls_from_api_counter_(0),
@@ skipping 1136 matching lines @@
   // Then check whether this scope intercepts.
   if ((flag & intercept_mask_)) {
     intercepted_flags_ |= flag;
     return true;
   }
   return false;
 }
 
 }  // namespace internal
 }  // namespace v8