[api] Add a switch that controls if ES2015 tail call elimination feature 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 2863 matching lines @@
 std::string Isolate::GetTurboCfgFileName() {
   if (FLAG_trace_turbo_cfg_file == NULL) {
     std::ostringstream os;
     os << "turbo-" << base::OS::GetCurrentProcessId() << "-" << id() << ".cfg";
     return os.str();
   } else {
     return FLAG_trace_turbo_cfg_file;
   }
 }
 
+void Isolate::SetTailCallEliminationEnabled(bool enabled) {
+  if (is_tail_call_elimination_enabled_ == enabled) return;
+  is_tail_call_elimination_enabled_ = enabled;
+  // This is a big hammer but we don't expect this to happen frequently.
+  internal::Deoptimizer::DeoptimizeAll(this);
+}
 
 // Heap::detached_contexts tracks detached contexts as pairs
 // (number of GC since the context was detached, the context).
 void Isolate::AddDetachedContext(Handle<Context> context) {
   HandleScope scope(this);
   Handle<WeakCell> cell = factory()->NewWeakCell(context);
   Handle<FixedArray> detached_contexts(heap()->detached_contexts());
   int length = detached_contexts->length();
   detached_contexts = factory()->CopyFixedArrayAndGrow(detached_contexts, 2);
   detached_contexts->set(length, Smi::FromInt(0));
@@ skipping 82 matching lines @@
   // Then check whether this scope intercepts.
   if ((flag & intercept_mask_)) {
     intercepted_flags_ |= flag;
     return true;
   }
   return false;
 }
 
 }  // namespace internal
 }  // namespace v8