fix(sidenav): remove min-width

Author: mmalerba

src/lib/sidenav/drawer.scss

@@ -106,7 +106,6 @@ $mat-drawer-over-drawer-z-index: 4;
   top: 0;
   bottom: 0;
   z-index: 3;
-  min-width: 5vw;
   outline: 0;
   box-sizing: border-box;
   overflow-y: auto; // TODO(kara): revisit scrolling behavior for drawers