Review all sniffs for compatibility with PHPCS >= 4.0

Development on PHPCS 4.x has started a while back.

While there is no timeline known for when it will be ready/released, some (breaking) changes which PHPCS 4.x will contain are already known.

Notable changes as known at the time of writing this:
* The minimum supported PHP version is slated to become PHP 7.2.
* Support for the PEAR installation method will be removed.
* Support for JS and CSS sniffs will be removed.
* Support for the "old-style" ignore annotations, like `@codingStandardsIgnoreLine` will be removed. These were deprecated in PHPCS 3.2.0.
* Support for the "old-style" array properties in rulesets, where array items would be passed via a comma separated value instead of as individual items. This was deprecated in PHPCS 3.3.0.
* Deprecated tokens will be removed, most notably `T_ARRAY_HINT` and `T_RETURN_TYPE` which were both deprecated in PHPCS 3.3.0.

I expect most of this won't have much effect on the sniffs in VIPCS. If/when more changes become known, I will update the above list.

However, a decision is needed about the future of the sniffs which look at JS/CSS code. There is no urgency (yet), but I'm opening this issue now to raise awareness and open the discussion about this.

特定のファイルやテストは指定されていません。まず、一覧にある PHPCS 4.x の変更に対してすべての VIPCS sniffs を確認し、その後、JavaScript および CSS sniffs を削除するか維持するかについての議論を確認してください。互換性に関する調査結果を文書化し、影響を受ける sniffs について決定に至れば完了です。

索引モデルが issue の本文から書いたものです。