NOTE: Several WebPack plugins could not be updated as all plugins within
WebPack's "webpack-contrib" have dropped support for WebPack v4
entirely, but Closure Compiler only supports WebPack v4.
The SSO provider list unexpectedly shrinks when the invalid login
"shake" animation plays due to the use of "display: table-row" vs. the
login form's own use of "display: table-cell". Migrating the SSO
provider list to a simple absolutely-positioned div corrects this and
matches the way the Guacamole version is rendered.
