`Tags::Base#select_content_tag`.

Previously, passing a falsey value to `include_blank` would be ignored if the
field was required, and a blank line would still be inserted. The following will
now raise instead of quietly failing:

`select("post", "category", %w(a required field), { include_blank: false }, required: 'required')`

This reverts commit a9d58c77, reversing
changes made to 041c2c87.

Reason: The old behavior is how it was working in previous version of
Rails since 4.0.x so it is not safe to backport to a stable branch.

See https://github.com/rails/rails/issues/19626#issuecomment-89862258
and https://github.com/rails/rails/pull/15050#issuecomment-45333449

When one rendered a partial template without specifying an object
or a collection (e.g. <%= render partial: 'partial_name' %>), Rails
would make an object called :partial_name available in local_assigns.
I don't think this was the intended behavior, since no local variable
called 'partial_name' gets defined in the view.

In help text for method, dynamic value makes it hard to understand, so replaced with static value matching with example above

Should be ApplicationController not ApplicationController::Base

This reverts commit d459b001, reversing
changes made to 4d4950fa.

😓

The block is not supposed to be passed to `link_to`. It's used for a
customized behavior of the `condtion = false` case. The docs
illustrate that like so:

```
<%=
   link_to_if(@current_user.nil?, "Login", { controller: "sessions", action: "new" }) do
     link_to(@current_user.login, { controller: "accounts", action: "show", id: @current_user })
   end
%>
```

The documentation previously stated that calling `translate(".foo")` was
equivalent to calling `I18n.translate("people.index.foo")` which is
incorrect due to the various other functions of the `translate` view
helper. This has been fixed.

Additionally, a note about forcing the view helper to re-raise
exceptions was added to the section detailing the handling of missing
translations.

Other cleanup includes:

* Consistent formatting of code
* Stop indenting bulleted list as a code sample
* Tighten some of the language
* Wrap at 80 characters.

add block to link_to_if when condition is true

Added informations about :host options for each url helper
(#javascript_url, #video_url, #stylesheet_url, etc) based on #asser_url
method.

This commit fixes issue #19626
Don't need to check layout conditions if there is no condition

test for parent layout bug fix

4.2.1 introduced a change to the way `translate`/`t` works with an
option of `default: [[]]`. In 4.2.0, this would give a default value of
`[]`, but in 4.2.1, it leads to a missing translation.

`default: [[]]` is again allowed for cases where a default of `[]` is
needed.

This addresses GitHub issue 19640.

https://github.com/ruby/ruby/pull/579 - there is a new optimization
since ruby 2.2

Previously regexp patterns were faster (since a string was converted to
regexp underneath anyway). But now string patterns are faster and
better reflect the purpose.

  Benchmark.ips do |bm|
    bm.report('regexp') { 'this is ::a random string'.gsub(/::/, '/') }
    bm.report('string') { 'this is ::a random string'.gsub('::', '/') }
    bm.compare!
  end
  # string: 753724.4 i/s
  # regexp: 501443.1 i/s - 1.50x slower

No need to merge hashes when simply setting options does the job.

The previous change 92a3c8dc improved
this example, but calling .create + #valid? ends up running validations
twice, and we don't want to showcase that.

Lets use the normal use case of building a new object and calling #save
on it, which is what a basic scaffold with Active Record does.

[ci skip]