Given an element added to an unknown shadowRoot like this:
var root = unknownHostElement.createShadowRoot();
root.appendChild(document.createElement('x-foo'));
An exception will occur due to the fact that it's assumed that the dom host of the x-foo element has a known styling api which can be interrogated. In this case the dom host of x-foo is not a Polymer element. We'll need to make the property resolver smarter about finding a styling host to avoid this problem and ensure that elements in unknown hosts are properly styled.
Given an element added to an unknown shadowRoot like this:
An exception will occur due to the fact that it's assumed that the dom host of the
x-fooelement has a known styling api which can be interrogated. In this case the dom host ofx-foois not a Polymer element. We'll need to make the property resolver smarter about finding a styling host to avoid this problem and ensure that elements in unknown hosts are properly styled.