fix(toolbar): Use transparent bg for menu icon to avoid IE 11 bug (#1909)
fix(toolbar): Use transparent bg for menu icon to avoid IE 11 bug (#1909)

IE 11 renders the toolbar menu icon with a grey background when the icon's `background-color` is set to `inherit`. Changing the value to `transparent` fixes the bug and doesn't seem to have any adverse affects in other browsers.

Fixes #881

![Screenshot comparison of the bug and the fix](https://user-images.githubusercontent.com/409245/34734739-bd3a7a4c-f521-11e7-8202-c5e6c9b03b0e.png)
material-components/material-components-web,material-components/material-components-web,material-components/material-components-web