This is commit is just the output of running the syntax updater on the
files in the internal/compiler/widgets directory.
No extra manual steps were done.
Note: In order to run the updater, I did a hack so that the updater wouldn't
choke on internal item used by the styles by commenting out the check in
ElementType::lookup_type_for_child_element
* Add `StateLayer` component
* Add `Ripple` component (used by StateLayer)
* use `StateLayer` in material `Button`
* use `StateLayer` in material `Item`
