14294 - Fixes 'back' functionality after switching a store view.

[Mobecls]

Description

Modifies switcher-option's link Magento/Store/view/frontend/templates/switch/languages.phtml template.

Fixed Issues (if relevant)

1. Since MagentoCE2.1.11, after swithing store view, ___store=xx is added to url. Breaks 'back' functionality. #14294: Since MagentoCE2.1.11, after swithing store view, ___store=xx is added to url. Breaks 'back' functionality.

Contribution checklist

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• All automated tests passed successfully (all builds on Travis CI are green)

[magento-cicd2]

All committers have signed the CLA.

[Mobecls]

@VladimirZaets, could you, please, help what exactly should I fix to pass the tests https://travis-ci.org/magento/magento2/jobs/389750567. Is that my fault the test shows these errors "Warning: PhantomJS timed out, possibly due to an unfinished async spec.� Use --force to continue." and "Aborted due to warnings."?

[magento-engcom-team]

Hi @Mobecls. Thank you for your contribution.
We will aim to release these changes as part of 2.3.1.
Please check the release notes for final confirmation.

[Mobecls]

cool, thanks