Some icons have `stroke: none` by default

[daneah]

Expected behavior Icons have a predictable stroke color without having to make changes.

Actual behavior All icons except the save icon have a black stroke by default, but save has stroke: none.

Steps to reproduce the issue

1. Visit the Icon names story
2. Inspect any icon
3. Look for the explicit stroke property we set for all the example icons and turn it off
4. Notice the save icon becomes invisible