iron-icons is a utitliy import that includes the definition for the
iron-iconset-svg element, as well as an import for the default icon set.
iron-icons directory also includes imports for additional icon sets that can be loaded into your project.
Example loading icon set:
<link rel="import" href="../iron-icons/maps-icons.html">
To use an icon from one of these sets, first prefix your
iron-icon with the icon set name, followed by a colon, ":", and then the icon id.
Example using the directions-bus icon from the maps icon set:
See iron-icon for more information about working with icons.