Revert "Re-optimize SVG"
This reverts commit 331566bc.
Revert "Move homepage-hero.svg to an img tag"
This reverts commit c24acf8d.
Temporarily reverting #31761 due to the Safari issue @mdo mentioned https://github.com/twbs/bootstrap/pull/31761#issuecomment-700395676. We'll have another try at it in alpha3.