Remove 'defer' from Google Analytics snippet

[coliff]

This removes 'defer' from the Google Analytics script.

• It was only included in H5BP as it added non-blocking support for older browsers, but as H5BP doesn't support IE8/IE9 anymore this is no longer needed. (REF: Simplify analytics snippet using async & defer #1696 (comment))
• It has no benefit if ran at the bottom of the page anyway (REF: script[defer] doesn't work in IE<=9  lazyweb-requests#42 (comment))
• It changes the execution time of the analytics.js script on all browsers and could negatively impact analytics tracking. (REF: Simplify analytics snippet using async & defer #1696 (comment) )
• The official Google Analytics snippet doesn't use/advise 'defer' in their async snippet (REF: https://developers.google.com/analytics/devguides/collection/analyticsjs/#alternative_async_tracking_snippet)
• Removing defer reduces the uncompressed page-weight by 6 bytes 🤓 )

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

Pull requests should be thought of as a conversation. There will be some back and forth when trying to get code merged into this or any other project. With all but the simplest changes you can and should expect that the maintainers of the project will request changes to your code. Please be aware of that and check in after you open your PR in order to get your code merged in cleanly.

Thanks!

[roblarsen]

👍