Small comment update according to PSR-2

See [PSR-2](http://www.php-fig.org/psr/psr-2/) paragraph 5.2

> There MUST be a comment such as `// no break` when fall-through is intentional in a non-empty case body.

Related to #11181
minor #11182 Small comment update according to PSR-2 (apfelbox)

This PR was submitted for the master branch but it was merged into the 2.3 branch instead (closes #11182).

Discussion
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Small comment update according to PSR-2

See [PSR-2](http://www.php-fig.org/psr/psr-2/) paragraph 5.2

> There MUST be a comment such as `// no break` when fall-through is intentional in a non-empty case body.

Related to #11181

Commits
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31b1dff Small comment update according to PSR-2