WebGL2: support TexImage3D (#37718)

Add TexImage3D method to WebGL2RenderingContext

Testing: conformance2 should pass. Also it should get
http://webglsamples.org/WebGL2Samples/#texture_2d_array and
http://webglsamples.org/WebGL2Samples/#texture_3d running.
Fixes: #26511

Now Servo can run texture_2d_array and texture_3d samples!

![圖片](https://github.com/user-attachments/assets/41b87563-08b8-4db3-b503-12f3a61dbed7)

![圖片](https://github.com/user-attachments/assets/3c62a4de-35ea-488d-b2e5-00e3aed52090)

And it can now run three.js too!

![圖片](https://github.com/user-attachments/assets/d880aa92-a154-4895-aa06-b7919d1fc869)

---------

Signed-off-by: Wu Yu Wei <yuweiwu@pm.me>

components/shared/canvas/webgl.rs

@@ -364,6 +364,22 @@ pub enum WebGLCommand {
     VertexAttribPointer(u32, i32, u32, bool, i32, u32),
     VertexAttribPointer2f(u32, i32, bool, i32, u32),
     SetViewport(i32, i32, i32, i32),
+    TexImage3D {
+        target: u32,
+        level: u32,
+        internal_format: TexFormat,
+        size: Size2D<u32>,
+        depth: u32,
+        format: TexFormat,
+        data_type: TexDataType,
+        // FIXME: This should be computed on the WebGL thread.
+        effective_data_type: u32,
+        unpacking_alignment: u32,
+        alpha_treatment: Option<AlphaTreatment>,
+        y_axis_treatment: YAxisTreatment,
+        pixel_format: Option<PixelFormat>,
+        data: TruncatedDebug<IpcSharedMemory>,
+    },
     TexImage2D {
         target: u32,
         level: u32,
@@ -1437,6 +1453,7 @@ pub struct GLContextAttributes {
 pub struct GLLimits {
     pub max_vertex_attribs: u32,
     pub max_tex_size: u32,
+    pub max_3d_tex_size: u32,
     pub max_cube_map_tex_size: u32,
     pub max_combined_texture_image_units: u32,
     pub max_fragment_uniform_vectors: u32,