extension registry markup/split for webgl 1/2/both extensions

It's currently the case that some purely WebGL 1 related extensions are exposed on WebGL 2 contexts which shouldn't be (because they're WebGL 2 core). It's also the case that it's not clear in the extension registry overview, which extensions are WebGL 1, 2 or both.

The extension definitions have the ability to mark up against which specification they're written, and they can also specify in which version they become core (example quoted from EXT_frag_depth below)

<depends>
  <api version="1.0"/>
  <core version="2.0">
    <glsl version="300 es"/>
  </core>
</depends>

Would it make sense to mark up/divide the extension in the overview in some fashion?

Start by inspecting the extension definitions and the extension registry overview, focusing on the existing depends markup and the WebGL 1/2 distinctions described here. Compare how extensions are exposed on WebGL 1 and WebGL 2 contexts. Done means WebGL 1-only extensions are not exposed on WebGL 2, and the overview clearly identifies extensions available to WebGL 1, WebGL 2, or both.