[Interpreter] Add Ignition statistics JavaScript extension.

src/extensions/ignition-statistics-extension.h

+// Copyright 2016 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.
+
+#ifndef V8_EXTENSIONS_IGNITION_STATISTICS_EXTENSION_H_
+#define V8_EXTENSIONS_IGNITION_STATISTICS_EXTENSION_H_
+
+#include "include/v8.h"
+
+namespace v8 {
+namespace internal {
+
+class IgnitionStatisticsExtension : public v8::Extension {
+ public:
+  IgnitionStatisticsExtension()
+      : v8::Extension("v8/ignition-statistics", kSource) {}
+
+  v8::Local<v8::FunctionTemplate> GetNativeFunctionTemplate(
+      v8::Isolate* isolate, v8::Local<v8::String> name) override;
+
+  static void GetIgnitionDispatchCounters(
+      const v8::FunctionCallbackInfo<v8::Value>& args);
+
+ private:
+  static const char* const kSource;
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_EXTENSIONS_IGNITION_STATISTICS_EXTENSION_H_