[Polymer] update third_party polymer

third_party/polymer/v1_0/components-chromium/paper-dropdown-menu/paper-dropdown-menu-light-extracted.js

 (function() {
       'use strict';
 
       Polymer({
         is: 'paper-dropdown-menu-light',
 
         behaviors: [
           Polymer.IronButtonState,
           Polymer.IronControlState,
           Polymer.PaperRippleBehavior,
@@ skipping 256 matching lines @@
             cls += ' label-is-floating';
           }
           return cls;
         },
 
         _valueChanged: function() {
           // Only update if it's actually different.
           if (this.$.input && this.$.input.textContent !== this.value) {
             this.$.input.textContent = this.value;
           }
-
-          if (this.value || this.value === 0 || this.value === false) {
-            this._setHasContent(true);
-          } else {
-            this._setHasContent(false);
-          }
+          this._setHasContent(!!this.value);
         },
       });
     })();