[Interpreter] Add Ignition statistics JavaScript extension.

src/extensions/ignition-statistics-extension.cc

+// 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.
+
+#include "src/extensions/ignition-statistics-extension.h"
+
+#include "src/interpreter/bytecodes.h"
+#include "src/interpreter/interpreter.h"
+#include "src/isolate.h"
+
+namespace v8 {
+namespace internal {
+
+v8::Local<v8::FunctionTemplate>
+IgnitionStatisticsExtension::GetNativeFunctionTemplate(
+    v8::Isolate* isolate, v8::Local<v8::String> name) {
+  DCHECK_EQ(strcmp(*v8::String::Utf8Value(name), "getIgnitionDispatchCounters"),
+            0);
+  return v8::FunctionTemplate::New(
+      isolate, IgnitionStatisticsExtension::GetIgnitionDispatchCounters);
+}
+
+const char* const IgnitionStatisticsExtension::kSource =
+    "native function getIgnitionDispatchCounters();";
+
+void IgnitionStatisticsExtension::GetIgnitionDispatchCounters(
+    const v8::FunctionCallbackInfo<v8::Value>& args) {
+  DCHECK_EQ(args.Length(), 0);
+  DCHECK(FLAG_trace_ignition_dispatches);
+  args.GetReturnValue().Set(reinterpret_cast<Isolate*>(args.GetIsolate())
+                                ->interpreter()
+                                ->GetDispatchCountersObject());
+}
+
+}  // namespace internal
+}  // namespace v8