Various extension-related cleanup and simplifications.

src/extensions/gc-extension.h

Index: src/extensions/gc-extension.h
diff --git a/src/extensions/gc-extension.h b/src/extensions/gc-extension.h
index 8c25e7d84d5e286b763d22873ca1d7962d1a9cce..adc79fe3398b3a8e5c2cc486bb6f68b74f923492 100644
--- a/src/extensions/gc-extension.h
+++ b/src/extensions/gc-extension.h
@@ -35,12 +35,21 @@ namespace internal {
 
 class GCExtension : public v8::Extension {
  public:
-  explicit GCExtension(const char* source) : v8::Extension("v8/gc", source) {}
+  explicit GCExtension(const char* fun_name)
+      : v8::Extension("v8/gc",
+                      BuildSource(buffer_, sizeof(buffer_), fun_name)) {}
   virtual v8::Handle<v8::FunctionTemplate> GetNativeFunctionTemplate(
       v8::Isolate* isolate,
       v8::Handle<v8::String> name);
   static void GC(const v8::FunctionCallbackInfo<v8::Value>& args);
-  static void Register();
+
+ private:
+  static const char* BuildSource(char* buf, size_t size, const char* fun_name) {
+    OS::SNPrintF(Vector<char>(buf, size), "native function %s();", fun_name);
+    return buf;
+  }
+
+  char buffer_[50];
 };
 
 } }  // namespace v8::internal