Corrected a docblock
Fixed wrong @return type.
fix for forgetMiddleware function 

forgetMiddleware function was checking an object against a (string) class name so it would never match and remove the middleware.
Merge pull request #5473 from fzahabian/4.2

fix for forgetMiddleware function
Merge pull request #5463 from benti/4.2

Fixed wrong @return type.
Merge pull request #5323 from GrahamCampbell/4.2-morph

[4.2] Corrected A Docblock
Merge branch '4.2'