renamed test method after implementation rename in FileHelper
Merge branch 'master' of github.com:yiisoft/yii2

* 'master' of github.com:yiisoft/yii2:
  Reverted  changeset 595ac6d0beaed1ba95c9249262c003cc40a87802
  Fixes #833: added charset to json response.
fixed return value of Component::can*Property

return false, not null