Revert previous 3 commits.

Revert "Use updated ClassElement AST interface."

This reverts commit 57711a58292fb25cf35a5f58af80a3effbecea34.

Revert "Remove virtual property support and add support for function bind syntax."

This reverts commit 37ff3825793b92727ac96d9acd834c406cc8dcf4.

Revert "Remove private syntax support."

This reverts commit 31ad8a60561724cd98d833d89b748ef858c6d449.
Rework class definition translation to support declarations within the class body.
Add support for declarations within classes and private class declarations.