Fix for javascript "mixins" when 'urlArgs' is set in requirejs - issue 8221

[thelettuce]

This fixes the problem where if you add a "urlArgs" argument to a requirejs file, javascript mixins will stop working. For example if you add the line :
urlArgs:urlArgs: "bust=2017-04-21"
to Magento_Theme/templates/page/js/require_js.phtml - this will stop mixins.js from working.
See issue #8221

Description

The problem is due to 'urlArgs' adding a query string to the path variable. The function getMixins in mixins.js tries to reference config using the path variable, but as this includes the query string, it fails.
This change removes the query string from the path variable, allowing config to be referenced correctly.

Fixed Issues (if relevant)

1. Javascript "mixins" doesn't works if 'urlArgs' is in requirejs-config.js #8221: Javascript "mixins" doesn't works if 'urlArgs' is in requirejs-config.js

Manual testing scenarios

1. Add urlArgs:urlArgs: "bust=2017-04-21" to any require-js config file on your site.
2. Test a module that uses javascript mixins or a plugin such as "Fooman GoogleAnalyticsPlus" that uses them.
3. They will now work.

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-team]

@thelettuce thank you for your contribution. Your Pull Request has been successfully merged