Auto merge of #19040 - MortimerGoro:webgl2_extensions, r=emilio

Add support for filtering WebGL extensions based on WebGL version

<!-- Please describe your changes on the following line: -->

Add support for filtering WebGL extensions based on WebGL version

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [ ] These changes fix #__ (github issue number if applicable).

<!-- Either: -->
- [x] There are tests for these changes OR
- [ ] These changes do not require tests because _____

<!-- Also, please make sure that "Allow edits from maintainers" checkbox is checked, so that we can help you if you get stuck somewhere along the way.-->

<!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. -->

<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/19040)
<!-- Reviewable:end -->

components/script/dom/webglrenderingcontext.rs

@@ -252,7 +252,7 @@ impl WebGLRenderingContext {
                 current_vertex_attrib_0: Cell::new((0f32, 0f32, 0f32, 1f32)),
                 current_scissor: Cell::new((0, 0, size.width, size.height)),
                 current_clear_color: Cell::new((0.0, 0.0, 0.0, 0.0)),
-                extension_manager: WebGLExtensions::new()
+                extension_manager: WebGLExtensions::new(webgl_version)
             }
         })
     }