When permalink data is available, display a permalink using
the current page title, instead of a plain link to the section
at the time of subscription.
Consolidate and clean up some existing permalink code.
Bug: T306373
Change-Id: Ie2f63cbfdbfa703530205201dfcfb0e5ad053b35
* Keep the information about this in the API result, which we were
previously omitting
* Use it instead of duplicating the logic client-side
Bug: T356131
Change-Id: I7e7342e9d94a171b5ef56e646871c18c8c39c44c
In production, indexing the full history of every page will take
too long, so we can't rely on being able to find the target heading
text in the history of the current page.
When this search fails, fall back to the following searches:
* The heading appears in the current revision of a sub-page
* The heading appears anywhere on the wiki, but only once
Bug: T356276
Change-Id: I90e92cb9c85aaf6fb2355f842450981bbe6abf2d
* Looks for heading IDs matching "h-<heading text>-%" that once
existed on the target page.
* For such IDs, finds where those items currently exist,
presumably in an archive.
Pros:
* Doesn't need to know anything about the local wiki's archiving
conventions, so can be deployed universally.
Cons:
* ID conflicts will return matches in unrelated archives, e.g.
MassMessages.
Bug: T349653
Change-Id: Ie94efd0503e9f4689d3421babe445f9f4e2b4fb7
