Move elements/ to ui/

appengine/swarming/ui/res/imp/common/interval-timer.html

 <!--
   Copyright 2016 The LUCI Authors. All rights reserved.
   Use of this source code is governed under the Apache License, Version 2.0
   that can be found in the LICENSE file.
 
   The interval-timer element fires the trigger event repeatedly using a
   configurable property.
 
   Properties:
     period - The number of seconds that should elapse before the trigger event fires.  After
@@ skipping 31 matching lines @@
             this.fire('trigger');
             // refire event
             this._periodChanged(period);
           }.bind(this), period * 1000);
         }
       },
     });
   }());
   </script>
 </dom-module>