Allow startup with missing V8 snapshot file.

gin/public/isolate_holder.h

Index: gin/public/isolate_holder.h
diff --git a/gin/public/isolate_holder.h b/gin/public/isolate_holder.h
index bf0db6c2513d27bdd0f63a09c9916183e94f40c4..16472937e281ae5a846a532b4df876511f31a268 100644
--- a/gin/public/isolate_holder.h
+++ b/gin/public/isolate_holder.h
@@ -40,7 +40,10 @@ class GIN_EXPORT IsolateHolder {
 
   // Should be invoked once before creating IsolateHolder instances to
   // initialize V8 and Gin. In case V8_USE_EXTERNAL_STARTUP_DATA is
-  // defined, V8's initial snapshot should be loaded (by calling
+  // defined, V8's initial natives should be loaded (by calling
+  // V8Initializer::LoadV8NativesFromFD or
+  // V8Initializer::LoadV8Natives) before calling this method.  If the
+  // snapshot file is available, it should also be loaded (by calling
   // V8Initializer::LoadV8SnapshotFromFD or
   // V8Initializer::LoadV8Snapshot) before calling this method.
   static void Initialize(ScriptMode mode,