Links from WebGL 1.0 to OpenGL ES 2 spec broken

References in WebGL 1.0 to OpenGL ES 2 have the form

```
http://www.khronos.org/registry/gles/specs/2.0/es_full_spec_2.0.25.pdf#nameddest=section-4.4.3
```

but the Khronos registry no longer uses the document version in the file name. There is only `es_full_spec_2.0`.

I thought about filing a bug on the OpenGL registry but all versions of OpenGL ES specs there now use only the OpenGL ES version in the file name.

Search the WebGL 1.0 source for references using the obsolete es_full_spec_2.0.25.pdf filename. Check the corresponding Khronos registry links and update them to the current es_full_spec_2.0 path, preserving the section anchors. Done means the referenced OpenGL ES 2 specification links resolve correctly.

Written by the indexing model from the issue text.