Fix disabled buttons

Change-Id: Ic693e48b614a72eaf520d4df54e4993ddb3521bf
diff --git a/polygerrit-ui/app/elements/shared/gr-button/gr-button.html b/polygerrit-ui/app/elements/shared/gr-button/gr-button.html
index f63d7923..0c20b07 100644
--- a/polygerrit-ui/app/elements/shared/gr-button/gr-button.html
+++ b/polygerrit-ui/app/elements/shared/gr-button/gr-button.html
@@ -57,6 +57,10 @@
         background-color: var(--color-link);
         color: #fff;
       }
+      :host([primary][disabled]) paper-button[raised],
+      :host([disabled]) paper-button {
+        opacity: .5;
+      }
       :host([link]) paper-button:hover,
       :host([link]) paper-button:focus,
       paper-button[raised]:hover,
@@ -108,7 +112,7 @@
         color: #aaa;
       }
     </style>
-    <paper-button raised="[[!link]]">
+    <paper-button raised="[[!link]]" disabled="[[disabled]]">
       <content></content>
       <i class="downArrow"></i>
     </paper-button>