Auto merge of #24176 - jdm:no-gleam, r=asajeffrey

Replace use of gleam in webgl with sparkle.

Rely on https://github.com/servo/sparkle for the GL bindings required to implement Servo's WebGL stack. This does not touch the GL usage in the compositor or webrender, which continue to rely on https://github.com/servo/gleam. This means that any breaking changes to the public GL bindings interface (such as required by https://github.com/servo/servo/pull/24111) only require updating rust-offscreen-rendering-context and rust-webvr, rather than many other crates that are out of our direct control.

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- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] There are tests for these changes

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components/script/dom/webgl_extensions/extensions.rs

@@ -20,9 +20,9 @@ use crate::dom::webglrenderingcontext::WebGLRenderingContext;
 use crate::dom::webgltexture::TexCompression;
 use canvas_traits::webgl::{GlType, WebGLVersion};
 use fnv::{FnvHashMap, FnvHashSet};
-use gleam::gl::{self, GLenum};
 use js::jsapi::JSObject;
 use malloc_size_of::MallocSizeOf;
+use sparkle::gl::{self, GLenum};
 use std::collections::HashMap;
 use std::iter::FromIterator;
 use std::ptr::NonNull;