[third_party] add polymer 1.2.3

polymer_1.2.3/bower_components/iron-resizable-behavior/iron-resizable-behavior.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
 The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
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@@ skipping 173 matching lines @@
         return;
       }
 
       this._notifyingDescendant = true;
       descendant.notifyResize();
       this._notifyingDescendant = false;
     }
   };
 </script>