This is the first step of T259059: Upgrade to CodeMirror 6. This will only put us in a basic working state with CodeMirror 6, with everything behind a temporary feature flag. The actual syntax highlighting and other features are to follow.
- Using the basic CodeMirror package, identify which modules under the @codemirror namespace we need.
- Create new ext.CodeMirror.v6.WikiEditor module that is loaded when $wgCodeMirrorV6 is set or if the cm6enable=1 URL query parameter is set.
- Visually, enabling CodeMirror should give you a monospaced text editor without any syntax highlighting.
- Relevant features of WikiEditor should still work (no exhaustive testing necessary), and you should still be able to save the page, etc.
- Identify any other integrations that are apparently now broken, and document them (we're not going to enable $wgCodeMirrorV6 anytime soon so some breakage is expected)