Previously, the project used for running integration tests for Angular
Elements declared a component that used `ShadowDom` for view
encopsulation, but it did not include any tests to verify that the view
was updated correctly.
This commit adds the missing tests.
PR Close#39452
When using ViewEncapsulation.ShadowDom, Angular will not remove the child nodes of the DOM node a root Component is bootstrapped into. This enables developers building Angular Elements to use the `<slot>` element to do native content projection.
PR Close#24861
George Kalpakas
Pawel Kozlowski
Rob Wormald