Access translated GL shaders?

I am in the process of creating work-arounds for various ANGLE issues that vary across browsers and browsers' versions. To that end, I would like to get access to how ANGLE translated my GL shaders into the 3D API of the chosen backend. The WebGL extension, https://www.khronos.org/registry/webgl/extensions/WEBGL_debug_shaders/, is the one to get those string. However, how do I get those strings from C++? The extension GL_WEBGL_debug_shaders is listed in the extension string. I've tried the following:

1. emscripten_webgl_get_proc_address("glGetTranslatedShaderSourceANGLE") gives null.
2. emscripten_webgl_get_proc_address("glGetTranslatedShaderSource") gives null.
3. defining GL_GLEXT_PROTOTYPES before including GLES3/gl3.h and GLES2/gl2ext.h produces linker errors.

I've scoured the documentation and came up empty. Any hints?