Testing `ReservedWordTest` for all adapters

Other examples were removed in 53ff5fc6

[ci skip]

`ReservedWordTest` expects that any identifiers are quoted properly.
It should be tested for all adapters.

Remove assert_nothing_raised, as test is already testing the required concerns

load_schema! is overridden by attribute modules, so we need to wait
until it has returned.

Introduce mattr_accessor default option

Don't create extra assignment, just return

Fix typo on error message when route definition is ambiguous.

Fix formatting of `direct` and `resolve` doc [ci skip]

Change default application.js included in new Rails app [ci skip]

Remove a redundant default_scope tests

Make Rails welcome page responsive

[ci skip] Fix `scaffold_controller` generator usage

some typos and rephrasing in system test guide [ci skip]

Document support for composite primary keys

Prevent making bind param if casted value is nil

Remove the redundant `test_find_all_with_join` in AR

SystemTesting::Driver can register capybara-webkit and poltergeist

drivers.

When using `driver_by` with capybara-webkit or poltergeist,
SystemTesting::Driver will register the driver while passing
`screen_size` and `options` parameteres.

`options` could contain any option supported by the underlying driver.

Remove the pathname dependency from bin/update and bin/setup

Replace an outdated mention of `jquery_ujs` with `rails-ujs`

Fix articles layout in guides by eliminating W3C validator warnings [ci skip]

Correct a has_many association test

Simplify `assert_no_match %r{colname.*limit:}` regex