Various extension-related cleanup and simplifications.

src/bootstrapper.h

Index: src/bootstrapper.h
diff --git a/src/bootstrapper.h b/src/bootstrapper.h
index 4f63c87163f0e512c2fbc6b3bbb35c1d19605e9a..14dd1bd99753d78a44541286c0625e3e0cfc24dc 100644
--- a/src/bootstrapper.h
+++ b/src/bootstrapper.h
@@ -90,6 +90,7 @@ class SourceCodeCache BASE_EMBEDDED {
 class Bootstrapper {
  public:
   static void InitializeOncePerProcess();
+  static void TearDownExtensions();
 
   // Requires: Heap::SetUp has been called.
   void Initialize(bool create_heap_objects);
@@ -146,6 +147,12 @@ class Bootstrapper {
 
   explicit Bootstrapper(Isolate* isolate);
 
+  static v8::Extension* free_buffer_extension_;
+  static v8::Extension* gc_extension_;
+  static v8::Extension* externalize_string_extension_;
+  static v8::Extension* statistics_extension_;
+  static v8::Extension* trigger_failure_extension_;
+
   DISALLOW_COPY_AND_ASSIGN(Bootstrapper);
 };