I would recommend not going about adding any of the extension defines/entrypoints/etc. on extensions that we can't possibly support (or emulate) in WebGL. Some of these are GL3 and GL4 identifiers, which we don't currently have the capability of supporting, so it would be best that codebases go and #ifdef the uses of those out, instead of having a header that seemingly allows you to compile, but warns about missing symbols and fails at runtime.