Ask HN: programming environment for a student who has outgrown toy environment?

My middle-school child has been learning to program for a couple of years now. He's worked his way up through Scratch (MIT's drag-and-drop sprite environment) and CodeHS (a minimal JavaScript editor coupled with a simple graphics toolkit and a good introductory curriculum). He's ready for something more substantial, but I'm not sure where to turn.

CodeHS is nice for beginners, but it lacks basic IDE functionality, and is fixed to a small (400 x 400) canvas. In decreasing order of importance, my criteria for his next tool:

1. Basic IDE functionality, such as autocomplete, static error checking, multiple files, and a debugger.

2. Allow creating both graphical applications (e.g. games) and simple console-type programs.

3. Support publishing games and other simple applications as a web page, so he can show his work to friends and family.

4. Runtime environment is simple and lightweight (e.g. don't have to learn a complex UI toolkit).

5. IDE is lightweight and easy to learn.

6. Live in the cloud, so he can work from any computer.

7. Use a mainstream language.

Any recommendations?