Async Transformers

I was using Compiler API and basically changed program.emit at host.afterProgramCreate just like examples and hooked my transformers into emit function. But one thing i couldn't find anywhere is a async transformer. Im using PostCSS and some other stuff like that and implementing those to a single typescript compiler but some plugins are async in postcss and i cant use them at the moment. Is there any way to implement this that im missing or undocumented ? And in case somebody offers to use webpack my code is mostly javascript based and i need really good static analysis for it with type data included that's also reason i use typescript's api instead of using babel which have those cases mostly covered with plugins. I'm implementing all-in-one solution for my company/community project so ideally it needs to be inside typescript compiler.

Issue で示されている Compiler API のエントリポイントである program.emit と host.afterProgramCreate から始め、次に transformer のライフサイクルを、関係する非同期 PostCSS プラグインのライフサイクルと比較します。非同期 transformer がサポートされているかを明らかにするか、サポートに必要な具体的で範囲を限定した Compiler の変更を文書化できれば完了です。