script: Move WebGL DOM interfaces to script/dom/webgl/ (#38995)

Move interfaces defined by the WebGL spec to the `script/dom/webgl/
`module from `script/dom/`.

`script/dom/webgl*.rs` -> `script/dom/webgl/`
`script/dom/webgl_extensions` -> `script/dom/webgl/extensions`
`script/dom/webgl_validations` -> `script/dom/webgl/validations`

Testing: No changes, just a refactoring

Fixes (partially): #38901

Signed-off-by: Andrei Volykhin <volykhin.andrei@huawei.com>
Co-authored-by: Andrei Volykhin <volykhin.andrei@huawei.com>

components/script/dom/webgl/extensions/wrapper.rs

@@ -0,0 +1,88 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+use std::ptr::NonNull;
+
+use js::jsapi::JSObject;
+use malloc_size_of::MallocSizeOf;
+
+use super::{WebGLExtension, WebGLExtensionSpec, WebGLExtensions};
+use crate::dom::bindings::reflector::DomObject;
+use crate::dom::bindings::root::MutNullableDom;
+use crate::dom::bindings::trace::JSTraceable;
+use crate::dom::webgl::webglrenderingcontext::WebGLRenderingContext;
+use crate::script_runtime::CanGc;
+
+/// Trait used internally by WebGLExtensions to store and
+/// handle the different WebGL extensions in a common list.
+pub(crate) trait WebGLExtensionWrapper: JSTraceable + MallocSizeOf {
+    fn instance_or_init(
+        &self,
+        ctx: &WebGLRenderingContext,
+        ext: &WebGLExtensions,
+    ) -> NonNull<JSObject>;
+    fn spec(&self) -> WebGLExtensionSpec;
+    fn is_supported(&self, _: &WebGLExtensions) -> bool;
+    fn is_enabled(&self) -> bool;
+    fn enable(&self, ext: &WebGLExtensions);
+    fn name(&self) -> &'static str;
+}
+
+#[cfg_attr(crown, crown::unrooted_must_root_lint::must_root)]
+#[derive(JSTraceable, MallocSizeOf)]
+pub(crate) struct TypedWebGLExtensionWrapper<T: WebGLExtension> {
+    extension: MutNullableDom<T::Extension>,
+}
+
+/// Typed WebGL Extension implementation.
+/// Exposes the exact `MutNullableDom<DOMObject>` type defined by the extension.
+impl<T: WebGLExtension> TypedWebGLExtensionWrapper<T> {
+    pub(crate) fn new() -> TypedWebGLExtensionWrapper<T> {
+        TypedWebGLExtensionWrapper {
+            extension: MutNullableDom::new(None),
+        }
+    }
+}
+
+impl<T> WebGLExtensionWrapper for TypedWebGLExtensionWrapper<T>
+where
+    T: WebGLExtension + JSTraceable + MallocSizeOf + 'static,
+{
+    #[allow(unsafe_code)]
+    fn instance_or_init(
+        &self,
+        ctx: &WebGLRenderingContext,
+        ext: &WebGLExtensions,
+    ) -> NonNull<JSObject> {
+        let mut enabled = true;
+        let extension = self.extension.or_init(|| {
+            enabled = false;
+            T::new(ctx, CanGc::note())
+        });
+        if !enabled {
+            self.enable(ext);
+        }
+        unsafe { NonNull::new_unchecked(extension.reflector().get_jsobject().get()) }
+    }
+
+    fn spec(&self) -> WebGLExtensionSpec {
+        T::spec()
+    }
+
+    fn is_supported(&self, ext: &WebGLExtensions) -> bool {
+        self.is_enabled() || T::is_supported(ext)
+    }
+
+    fn is_enabled(&self) -> bool {
+        self.extension.get().is_some()
+    }
+
+    fn enable(&self, ext: &WebGLExtensions) {
+        T::enable(ext);
+    }
+
+    fn name(&self) -> &'static str {
+        T::name()
+    }
+}