##Polymer.PaperCheckedElementBehavior
Use Polymer.PaperCheckedElementBehavior to implement a custom element
that has a checked property similar to Polymer.IronCheckedElementBehavior
and is compatible with having a ripple effect.
##Polymer.PaperInkyFocusBehavior
Polymer.PaperInkyFocusBehavior implements a ripple when the element has keyboard focus.
##Polymer.PaperRippleBehavior
Polymer.PaperRippleBehavior dynamically implements a ripple
when the element has focus via pointer or keyboard.
NOTE: This behavior is intended to be used in conjunction with and after
Polymer.IronButtonState and Polymer.IronControlState.