fix(material/grid-list): Allow typography mixin to consume 2018 style configs

See angular#21059 for context.

Author: mmalerba

src/material/grid-list/_grid-list-theme.scss

@@ -1,5 +1,6 @@
 @import '../core/theming/palette';
 @import '../core/theming/theming';
+@import '../core/typography/typography';
 @import '../core/typography/typography-utils';
 @import '../core/style/list-common';
 
@@ -8,6 +9,7 @@
 @mixin mat-grid-list-color($config-or-theme) {}
 
 @mixin mat-grid-list-typography($config-or-theme) {
+  $config: mat-private-typography-normalized-config(mat-get-typography-config($config-or-theme));
   $config: mat-get-typography-config($config-or-theme);
   .mat-grid-tile-header,
   .mat-grid-tile-footer {