Let's not do this at this point. There are several reasons:
 * this is not directly related to the other change in this PR, nor to the issue it's fixing;
 * `autofocus` is used in the original JavaScript-based Polymer element that we used as the basis for this one: let's assume that the original authors knew what they were doing and analyze why they did it this way; it may be even possible that his analysis will make us want to change `focused` to `autofocus` elsewhere in our widgets/;
 * Even if `focused` was a better choice, this change wouldn't be complete: there are many references to `autofocus` in comments and examples under widgets/lib/spark-overlay/. If you fix them all here, they will drown the core change here, which is the one in spark-button.