A number of components used `overflow-y`: scroll, which forces
scrollbars to be always visible. To work around this, `commons.scss` hid
webkit scrollbars globally. There are two problems with this: on
non-webkit browsers, scrollbars are visible even when they are
unnecessary; and scrollbars are hidden in webkit browsers, even on
elements where they may be desirable.
Instead, we use `overflow-y: auto`, and hide webkit scrollbars on
specific components when necessary. Unfortunately, this requires using
element selectors, but this is the trade-off for better supporting
non-webkit browsers and allowing scrollbars on regular elements (like
body).
Fixes#218
Lucas Correia