Update Polymer from 1.2.1 -> 1.2.3

third_party/polymer/v1_0/components-chromium/paper-item/paper-item-shared-styles.html

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 This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
 The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
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@@ skipping 20 matching lines @@
         position: relative;
         outline: 0;
         @apply(--paper-item-focused);
       }
 
       :host(:focus):before {
         @apply(--layout-fit);
         content: '';
         background: currentColor;
         opacity: var(--dark-divider-opacity);
+        pointer-events: none;
 
         @apply(--paper-item-focused-before);
       }
     </style>
   </template>
 </dom-module>