upgrade tubalmartin/cssmin to 4.1.0

[AntonEvers]

Description

According to https://github.com/tubalmartin/YUI-CSS-compressor-PHP-port/blob/master/README.md#v410-16-may-2017: Performance: 2x times faster than v4.0.0 after code profiling

Also minor enhancements like:

[target='_blank']       => [target=_blank]
[type="something"]      => [type=something]
background: transparent => background: 0 0
background: none        => background: 0 0
#f00                    => red
padding: 20px 20px      => padding 20px
0.12                    => .12

total min.css size reduced by 2563 bytes (from 1732225 to 1729662)

Fixed Issues (if relevant)

1. none as if yet

Manual testing scenarios

1. Before upgrading this package, generate minified css files, then run cat `find pub/static/ -name *.min.css -print | sort` > 3.0.0.min.css
2. Upgrade the package, generate minified css again and run cat `find pub/static/ -name *.min.css -print | sort` > 4.1.0.min.css
3. Compare the two files. you will see the enhancements like above.
4. Visually compare the site before and after and see that there are no changes.

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)

[AntonEvers]

@ishakhsuvarov how do you want to approach the failed integration test (INDEX=3). Is it good to first do the review and then change the minified css to compare against in

Magento\Framework\View\Asset\MinifierTest::testCSSminLibrary
Magento\Framework\View\Asset\MinifierTest::testCssMinification
Magento\Framework\View\Asset\MinifierTest::testDeploymentWithMinifierEnabled

or do you want me to change them right away in this PR?

[ishakhsuvarov]

@ajpevers I will try to get someone from the Magento Frontend guys to review it.

[okorshenko]

Hi @ajpevers your Pull Request has been merged to develop branch. Thank you