Use the non-deprecated way to set the button labels

Tools/GardeningServer/ui/ct-failure-card.html

Index: Tools/GardeningServer/ui/ct-failure-card.html
diff --git a/Tools/GardeningServer/ui/ct-failure-card.html b/Tools/GardeningServer/ui/ct-failure-card.html
index abf3deeec9baa4fd6eebf9ce9c5397b7ba98660b..32e63b5957b575f938526b39f8fc86ddf5654c18 100644
--- a/Tools/GardeningServer/ui/ct-failure-card.html
+++ b/Tools/GardeningServer/ui/ct-failure-card.html
@@ -70,12 +70,12 @@ found in the LICENSE file.
           commits="{{ commits }}"></ct-commit-list>
     </div>
     <div id="buttons">
-      <paper-button id="examine" on-tap="{{ examine }}">Examine</paper-button>
+      <paper-button id="examine" on-tap="{{ examine }}" label="Examine"></paper-button>
       <template if="{{ !group.isSnoozed }}">
-        <paper-button id="snooze" on-tap="{{ snooze }}">Snooze</paper-button>
+        <paper-button id="snooze" on-tap="{{ snooze }}" label="Snooze"></paper-button>
       </template>
       <template if="{{ group.isSnoozed }}">
-        <paper-button id="snooze" on-tap="{{ unsnooze }}">Unsnooze</paper-button>
+        <paper-button id="snooze" on-tap="{{ unsnooze }}" label="Unsnooze"></paper-button>
       </template>
     </div>
   </template>