Make it possible to customize menu button content.

Googler · nshahan · commit f83198c691d6 · 2018-01-19T14:36:29.000-08:00
PiperOrigin-RevId: 182346419
diff --git a/lib/material_menu/material_menu.html b/lib/material_menu/material_menu.html
@@ -18,6 +18,7 @@
       [icon]="menu.uiIcon">
   </material-icon>
   <span *ngIf="buttonText != null">{{buttonText}}</span>
+  <ng-content select="[menu-button]"></ng-content>
 </material-button>
 <menu-popup
     *ngIf="hasSubmenu"
