Cleanup and extend `METHOD_DEF`

  * Fixes #2949: Detect reserved names (not only for instance methods)
  * Don't assign names which might result in incorrect `super` calls
Fixes #3232 -- Tag all class properties `static`

(and remove duplicate `context` assigment)
Merge pull request #3237 from marchaefner/fixSuper

Fix super-related tagging of `Code` nodes