Given the following: 

1. a user navigates to: foo.com/#footer

2. at the requested url inside some shadowRoot we have:
<div>
SR
  <footer id="footer"></footer>

In this case, the #footer resource should be navigated to (page scrolls to it) even though it is inside a shadowRoot. There is one url for a page and it must be shared by all the shadowRoots. 

Since id's are scoped inside ShadowDOM, there may be a lot of duplicates page-wide. So, which one should be followed? The answer here is to do what browsers do now in this case: navigate to the first fragment identifier.