JM+TI sets this flag to signal that a function shouldn't be inlined. Ion also checks this flag, but in many cases Ion can inline these functions just fine. This prevents us from inlining some functions on Kraken imaging-darkroom - JM sets the flag there because it cannot generate native call stubs in inlined functions.
Created attachment 633466 [details] [diff] [review] Patch OBJECT_FLAG_UNINLINEABLE is set to either prevent us from expanding inlined frames over and over again or when JM wants to generate a native call/getter IC. With Ion we don't have to expand inline frames and we can generate ICs in inlined functions so I don't think we need to check this flag.