Legacy parser can now output headings using a more accessible markup,
which is also identical to the markup used by the Parsoid parser.
Changes to client-side JS and CSS necessary to support the new markup
have already been merged in earlier commits.
includes/skins/Skin.php
includes/ServiceWiring.php
* Define a new skin option, 'supportsMwHeading', which can be used
to toggle the new markup per-skin.
* Update the built-in fallback skin to enable it. This affects the
output in parser tests.
docs/config-schema.yaml
includes/config-schema.php
includes/config-vars.php
includes/MainConfigNames.php
includes/MainConfigSchema.php
* Add a new configuration setting, 'ParserEnableLegacyHeadingDOM',
which can be used to toggle the new markup per-site.
includes/OutputTransform/Stages/HandleSectionLinks.php
* Output new heading HTML for skins that enabled the option.
tests/*
* Duplicate parser tests that cover heading generation to cover both
new and old markup. Update other parser tests to use new markup.
* Add some unit and integration tests for the behavior of the skin
option and some parser tests for edge cases of the new markup.
Bug: T13555
Change-Id: I1180169a8e83af834c2984ba16089e6277f2a8dd
