Cleanup the extensions code to avoid the duplication that was introduced in the quick fix to turn t…

runtime/bin/extensions.h

Index: runtime/bin/extensions.h
diff --git a/runtime/bin/extensions.h b/runtime/bin/extensions.h
index e8284c459d5fc0edd5253550db39c19f0f2f9386..8c172b85ff89cb840f00dff4c4b766ce941dd1bd 100644
--- a/runtime/bin/extensions.h
+++ b/runtime/bin/extensions.h
@@ -26,11 +26,7 @@ class Extensions {
   static void* ResolveSymbol(void* lib_handle, const char* symbol);
 
  private:
-  static Dart_Handle LoadExtensionLibrary(const char* library_file,
-                                          void** library);
-  static Dart_Handle ResolveSymbol(void* lib_handle,
-                                   const char* symbol,
-                                   void** init_func);
+  static Dart_Handle GetError();
 
   // The returned string must be freed.
   static char* Concatenate(const char** strings);