Add a use counter API

src/api.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/api.h"
 
 #include <string.h>  // For memcpy, strlen.
 #ifdef V8_USE_ADDRESS_SANITIZER
 #include <sanitizer/asan_interface.h>
 #endif  // V8_USE_ADDRESS_SANITIZER
@@ skipping 6698 matching lines @@
 void Isolate::SetAutorunMicrotasks(bool autorun) {
   reinterpret_cast<i::Isolate*>(this)->set_autorun_microtasks(autorun);
 }
 
 
 bool Isolate::WillAutorunMicrotasks() const {
   return reinterpret_cast<const i::Isolate*>(this)->autorun_microtasks();
 }
 
 
+void Isolate::SetUseCounterCallback(UseCounterCallback callback) {
+  reinterpret_cast<i::Isolate*>(this)->SetUseCounterCallback(callback);
+}
+
+
 String::Utf8Value::Utf8Value(v8::Handle<v8::Value> obj)
     : str_(NULL), length_(0) {
   i::Isolate* isolate = i::Isolate::Current();
   if (obj.IsEmpty()) return;
   ENTER_V8(isolate);
   i::HandleScope scope(isolate);
   TryCatch try_catch;
   Handle<String> str = obj->ToString();
   if (str.IsEmpty()) return;
   i::Handle<i::String> i_str = Utils::OpenHandle(*str);
@@ skipping 879 matching lines @@
   Isolate* isolate = reinterpret_cast<Isolate*>(info.GetIsolate());
   Address callback_address =
       reinterpret_cast<Address>(reinterpret_cast<intptr_t>(callback));
   VMState<EXTERNAL> state(isolate);
   ExternalCallbackScope call_scope(isolate, callback_address);
   callback(info);
 }
 
 
 } }  // namespace v8::internal