PACK_IMAGE_HEIGHT and PACK_SKIP_IMAGES are remnants of an older version of the spec, they were removed in GLES 3.0.1, and should be removed from WebGL.
As far as DRAW_BINDING goes, it seems like it should be DRAW_BUFFER<i> instead of DRAW_BINDING (DRAW_BUFFER<i> is missing from that list).
IMPLEMENTATION_COLOR_READ_FORMAT/TYPE do still exist in GLES3.0 and so also in WebGL 2.0, but they were also reintroduced in WebGL 1.0 last year, so they should not be in that table listing only new valid parameters. They are not for float textures, since
float framebuffer attachments and reading them are only added in EXT_color_buffer_float, but other read formats that might be allowed by the implementation.
Good that someone caught these issues, I submitted a pull request that fixes the list: https://github.com/KhronosGroup/WebGL/pull/843
Seeing as the WebGL2 spec does not outline any differences with what readPixels accepts I'm assuming it has remained the same and there is still no need for IMPLEMENTATION_COLOR_READ_FORMAT and IMPLEMENTATION_COLOR_READ_TYPE in WebGL 2 (and so should be removed from the getParameter table)
I'm working on WebGL 2 however, not 1, and WebGL 2 does use ES 3.0 so these should indeed exist on the WebGL2RenderingContext IDL.
DRAW_BINDING is not in any specification I could find (it's not in ES 2.0, ES 3.0, ES 3.1, GL 2.0, GL 3.0 or GL 4.0). What's that parameter?
I could not find it anywhere either but it definitely shows up here: https://www.khronos.org/registry/webgl/specs/latest/2.0/#3.7.1which is confusing, so maybe it shouldn't be on the getParameter table either.