abbr[title] still has border-bottom on v4-dev

Created by: davidstosik

Hello,

I wanted to comment on #16574 (closed), but it is closed and I can't reopen it, so I was not sure that would notify anyone. Sorry in advance if creating a new issue was bad.

The problem (abbr[title] should not have border-bottom) is still here on v4-dev. I get underline and dotted border-bottom:

(Screenshot was taken on Chrome v53 for Mac.) Here is a JSBin too.

_normalize.scss:112

//
// 1. Remove the bottom border in Firefox 39-.
// 2. Add the correct text decoration in Chrome, Edge, IE, Opera, and Safari.
//

abbr[title] {
  border-bottom: none; // 1
  text-decoration: underline; // 2
  text-decoration: underline dotted; // 2
}

_reboot.scss:114

// Abbreviations and acronyms
abbr[title],
// Add data-* attribute to help out our tooltip plugin, per https://github.com/twbs/bootstrap/issues/5257
abbr[data-original-title] {
  cursor: help;
  border-bottom: 1px dotted $abbr-border-color;
}

In the resulting boostrap.css, the reboot part goes lower than the normalize part, and the border ends up being shown.