Auto merge of #25752 - szeged:mmatyas__webgl_fns_framebuf_glparams, r=jdm

Add support for WebGL2 `MAX_COLOR_ATTACHMENTS` and `MAX_DRAW_BUFFERS`

Adds support for using the WebGL2 enums `MAX_COLOR_ATTACHMENTS` and `MAX_DRAW_BUFFERS` with `GetParameter`.

See https://www.khronos.org/registry/webgl/specs/latest/2.0/#3.7.2

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cc @jdm @zakorgy

---
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components/script/dom/webgl2renderingcontext.rs

@@ -535,6 +535,8 @@ impl WebGL2RenderingContextMethods for WebGL2RenderingContext {
             constants::UNIFORM_BUFFER_OFFSET_ALIGNMENT => {
                 Some(self.base.limits().uniform_buffer_offset_alignment)
             },
+            constants::MAX_COLOR_ATTACHMENTS => Some(self.base.limits().max_color_attachments),
+            constants::MAX_DRAW_BUFFERS => Some(self.base.limits().max_draw_buffers),
             _ => None,
         };
         if let Some(limit) = limit {