[Interpreter] Add Ignition statistics JavaScript extension.

src/bootstrapper.h

Index: src/bootstrapper.h
diff --git a/src/bootstrapper.h b/src/bootstrapper.h
index d1bf2011399d5204573ecdefb6eafc29f59ec127..5563eea043f6fa01715678937ef160b2d63ccd29 100644
--- a/src/bootstrapper.h
+++ b/src/bootstrapper.h
@@ -136,6 +136,7 @@ class Bootstrapper final {
   static v8::Extension* externalize_string_extension_;
   static v8::Extension* statistics_extension_;
   static v8::Extension* trigger_failure_extension_;
+  static v8::Extension* ignition_statistics_extension_;
 
   DISALLOW_COPY_AND_ASSIGN(Bootstrapper);
 };