This documentation should be in the guides.

Closes #16691

Merge pull request #16801 from eileencodes/refactor-scope_chain-on-through-refelction-to-eliminate-branch-in-eval_scope

Always add lambda to scope chain to eliminate branch in eval_scope

We convert all other scopes to lambda's so it makes sense that we should
always returns a lambda on a ThroughReflection as well. This eliminates
the need to check if the scope is a Relation.

Followup to PR #16762

Remove chain from parameters, it's no longer needed since chain and i
are being passed via next_reflection

Change name of `reflection` to `owner_reflection` because of shadow
variable warning. The last reflection will always be the owner.

[ci skip] Fix typo in rails guide for routing

Added a few more methods on Module/Class to the dangerous class methods
blacklist. (Technically, allocate and new are already protected currently because
we happen to redefine them in the current implantation.)

Closes #16792

This is a follow-up to ded17a49 to get the build passing on Travis.
As Travis has `ENV["RACK_ENV"]` set to `test` we need to reset that as well.

Warning looked like this:

```
/Users/senny/Projects/rails/activerecord/lib/active_record/associations/association_scope.rb:142: warning: shadowing outer local variable - reflection
```

* Renames _handle_render_options to _render_to_body_with_renderer, which is more
  intention-revealing.

* The name of the dynamically generated method for a renderer with key :js was
  "_render_option_js".

  That name is too weak. :js is an option if you see the render argument as just
  a generic options hash, but in the context of renderers that's the renderer
  key, is what identifies the renderer.

  Now "_render_with_renderer_js" is generated instead, which is crystal clear.

* The name of the dynamically generated method for the renderer was constructed
  using string literals in a few places. That is now encapsulated in a method.

* Since we were on it, also removed a couple of redundant selfs.

Add support for ARIA attributes in tags

Methods are not duplicable.

[Active Job] Try to deserialize with GlobalID only strings and globalids

Ship with rails-html-sanitizer instead.

Dont mess with default order engines load (4.1.6.rc1 regression)

[Joshua Cody & Yves Senn]

Closes #16757.

Prior to this patch schema loading rake tasks had the potential to leak a
connection to a different database. This had side-effects when rake tasks
operating on the current connection (like `db:seed`) were chained.

Fix for double ActiveJob::DeserializationErorr

reset_column_infomation shouldn't be part of the assertion.

use correct operator in query based on JSON document [ci skip]

Move column option handling to new_column_definition

When copying migrations some engines might depend on schema from other
engine so we can't blindly reverse all railties collection as that would
affect the order they were originally loaded. This patch helps to only
apply the order from engines specified in `railties_order`

TableDefinition#column is not called from `add_column`.
Use TableDefinition#new_column_definition for column option handling.

Fix failing tests in ActiveJob Adapter

Remove 'if exists' from drop table statement then use `table_exists?`

Since 'drop table if exists' statement does not always work with
some databases such as Oracle.