include anchor buttons

Author: andrewseguin

src/material-experimental/mdc-button/button-base.ts

@@ -150,6 +150,9 @@ export const MAT_ANCHOR_HOST = {
   // an unthemed version. If color is undefined, apply a CSS class that makes it easy to
   // select and style this "theme".
   '[class.mat-unthemed]': '!color',
+  // Add a class that applies to all buttons. This makes it easier to target if somebody
+  // wants to target all Material buttons.
+  '[class.mat-mdc-button-base]': 'true',
 };
 
 /**