Bump bower from 1.8.2 to 1.8.4

Bumps [bower](https://github.com/bower/bower) from 1.8.2 to 1.8.4.
- [Release notes](https://github.com/bower/bower/releases)
- [Changelog](https://github.com/bower/bower/blob/master/CHANGELOG.md)
- [Commits](bower/bower@v1.8.2...v1.8.4)

Signed-off-by: dependabot[bot] <support@dependabot.com>

yarn.lock

@@ -1094,8 +1094,8 @@ bootstrap@>=3.0.0:
   resolved "https://registry.yarnpkg.com/bootstrap/-/bootstrap-3.3.7.tgz#5a389394549f23330875a3b150656574f8a9eb71"
 
 bower@^1.8.0:
-  version "1.8.2"
-  resolved "https://registry.yarnpkg.com/bower/-/bower-1.8.2.tgz#adf53529c8d4af02ef24fb8d5341c1419d33e2f7"
+  version "1.8.4"
+  resolved "https://registry.yarnpkg.com/bower/-/bower-1.8.4.tgz#e7876a076deb8137f7d06525dc5e8c66db82f28a"
 
 brace-expansion@^1.1.7:
   version "1.1.8"