Scoped CustomElementRegistry polyfill based on proposal: https://github.com/justinfagnani/scoped-custom-elements

Technique: uses native CustomElements to register stand-in classes that delegate to the constructor in the registry for the element's scope; this avoids any manual treewalks to identify custom elements that need upgrading. Constructor delegation is achieved by constructing a bare HTMLElement, inspecting its tree scope (or the tree scope of the node it was created via) to determine its registry, and then applying the "constructor call trick" to upgrade it.

The code here captures some of the patterns I used in the "real estate" demo app discussed in my talk End to End Apps with Polymer from Polymer Summit 2017.

There are many ways to connect Redux to custom elements, and this demonstrates just one pattern. The most important aspects are to try and lazily-load as much of the otherwise global state management logic along with the components that need them (as shown via the lazyReducerEnhancer and addReducers calls in the connected components), and to consider the tradeoffs you make in terms of coupling components to the store.

The pattern shown here of creating a stateless component and then a subclass that connects it to the store addresses a potential desire to reuse app-level stateless components between more than one application context, so the subclass provides a degree of decoupling from the concrete store, at the expense of more boilerplate. If app com