Code Mirror Version Compatibility

I’m using codemirror for the python editor(Python 2.7). Everything worked perfectly. When I gave it for the build, our build will uglify the javascript using grunt files.

The problem is: Our grunt files are compatible with ES5. Build will fail if we use ES6. Since the javascript files are code mirror are in ES6, the build failed.

Is there any version of code with which is ES5?
Does that version support python-2.7 as the latest version?

Thank you!

The distributed code (via npm) in lib/ is ES5.