List background color is not themeable

[ns8482e]

Bug report

When changing $background for the theme, List's background is not updated, parent's background-color is applied,

Steps to reproduce

1. Define SCSS

   
   @use "@material/theme" with (
   $background: #121212,
   $surface: #121212,
   $on-surface:#fff
   );

@use "@material/drawer"; @use "@material/list";

@include list.core-styles; @include drawer.core-styles;

2. Define html 

```html
<aside class="mdc-drawer">
.....
</aside>
<ul class="mdc-list" role="group" aria-label="List with checkbox items">
......
</ul>

Actual behavior

List is taking backround-color from parent element not from the theme.

Expected behavior

It should take surface color provided in theme.

Screenshots

Your Environment:

Software	Version(s)
MDC Web	7.0.0
Browser	Chrome Version 84.0
Operating System	Windows 10

Possible solution

Define background-color using following

.mdc-list{
  @include theme.prop(background-color, surface);
}

[abhiomkar]

Thanks @ns8482e for reporting this bug.

MDC List does not seem to apply any background color, it is transparent with the background layer. This seems like a bug.