Show correct link color on cached result of Special:DeadendPages

Reaching this by doing a LinkBatch and than using
Linker::link instead of Linker::linkKnown.
This adds also the stub color to the link.

Bug: 56912
Change-Id: I516f95302546ccdf8d0fdc7101c2ff72daa5f2fb
Merge "Show correct link color on cached result of Special:DeadendPages"