WebStorm 8.0が Releaseされました！
This can be fixed mostly with adding some annotations to tell the editor meaning of the code.
But unfortunately, the problem cannot be fixed on this way, infrequently.
In this case, I fix as follows,
Open the project which has this problem. Click ‘File’ -> ‘Invalidate Caches/Restart…’ Click [Invalidate and Restart] button when opened the dialog.