I updated this archive to contain a build of Python 3.8 instead of the deprecated Python 2.7:
http://rdb.name/webgl-editor-and-dependencies.zip
It also includes the patch and command I used to build it. The Roaming Ralph sample and build script are included.
I also committed WebGL 2 support to the webgl-port branch, and I updated the online editor demo to use Python 3.8, WebAssembly and WebGL 2:
http://rdb.name/panda3d-webgl/editor.html