Use the non-deprecated way to set the button labels

Use label="" instead of the textContent

R=ojan@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/469423005

git-svn-id: svn://svn.chromium.org/blink/trunk@180312 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/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>