This patch has been in testing on ark.wiki.gg (with the platform's approval) for a few months now, and has yielded us significantly better extracts than the live algorithm. It brings Description2 closer to TextExtracts' level, but without its constraints. TextExtracts does not enable us to override descriptions as we see fit, requires internal API calls, and uses HtmlFormatter which has its own slew of problems.
I'm also raising MW requirement to 1.38: this change has not been tested with older versions, and I removed uses of old `getProperty` in favour of `getPageProperty` to clean up the code. I doubt this really matters much: support for 1.35 is about to end (if it hasn't already), and 1.38 itself is already EoL. It also appears that lately this extension only received forward-compatibility patches.
New provider leverages RemexHtml (used in core MediaWiki and Parsoid) to parse and process a page's HTML. For performance reasons (but also bit of practicality - it's unlikely that description derival needs full page text...) any HTML after the first <h1-6> heading is dropped and not parsed. However, this is just a precaution, on ARK we haven't noticed any performance degradation.
Two new configuration variables are added:
- `$wgUseSimpleDescriptionAlgorithm` (proposed default: false) determines which extract provider is used. `true` is the previous algorithm. `false` is the new Remex implementation.
- `$wgDescriptionRemoveElements` is an array of tag names and/or class names to strip out when generating extracts. This is only supported in the Remex provider, and would be hard to retrofit into the previous algorithm.
Depends-On: I04b00f99085f07f773212ee3eca8470eece34e9e
Change-Id: I8e6bf1f17443feac89f07e728d395e5a525bd4d1
