This reverts commit 2bad6058.

Conflicts:
	actionpack/CHANGELOG.md

Reason: This added a regression related with shoulda-matchers, since it
is expecting the instance variable @layouts

See https://github.com/thoughtbot/shoulda-matchers/blob/9e1188eea68c47d9a56ce6280e45027da6187ab1/lib/shoulda/matchers/action_controller/render_with_layout_matcher.rb#L74

This will introduce back #7459 but this stable release will be backward compatible.
Related with #8068.