Third pass updating vendor prefixes

[ntwb]

What issue # is this related to?

See #171, replaces PR #177 & PR #379

What is your WordPress.org username?

netweb

Screenshots (if appropriate)

Questions:

Please make sure all the below checkboxes have been checked before submitting your PR.

• [x] Are all the above sections filled out appropriately?
• [x] Have you read CONTRIBUTING.md?
• [x] Did you maintain a new line at the end of each file modified/added?
• [x] If this adds new js dependencies, did you add them to .jscsrc & .jshintignore?

Please understand that because of the size of this project, your PR may go stale and before someone can review it. If this is the case please rebase/refresh your PR and resolve any conflicts.

Thank you for taking the time to contribute to Twenty Seventeen!

[ntwb]

cc @davidakennedy