I think <base> and <link> work as expected, but it's good to have test to confirm it.
Spec is here.
Created attachment 134237 [details]
Comment on attachment 134237 [details]
View in context: https://bugs.webkit.org/attachment.cgi?id=134237&action=review
> + This test checks adding <base> or <link> in shadow root will not affect the
> + elements outside the shadow tree.
Outside _and_ inside?
Created attachment 134545 [details]
Patch for landing
Committed r112518: <http://trac.webkit.org/changeset/112518>