servo: Merge #13060 - webgl: Do validation of glScissor/glViewport(width, height) on the DOM side (from anholt:webgl-invalid-passed-params); r=emilio

<!-- Please describe your changes on the following line: -->
webgl: Do validation of glScissor/glViewport(width, height) on the DOM side

---
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- [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).

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- [X] There are tests for these changes OR
- [ ] These changes do not require tests because _____

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Avoids testcase CRASHes due to unexpected GL errors.

Source-Repo: https://github.com/servo/servo
Source-Revision: 11e8e42fd855c1078364c70926dfb1c888bdb7bb

servo/components/script/dom/webglrenderingcontext.rs

@@ -1526,6 +1526,10 @@ impl WebGLRenderingContextMethods for WebGLRenderingContext {
 
     // https://www.khronos.org/registry/webgl/specs/latest/1.0/#5.14.4
     fn Scissor(&self, x: i32, y: i32, width: i32, height: i32) {
+        if width < 0 || height < 0 {
+            return self.webgl_error(InvalidValue)
+        }
+
         self.ipc_renderer
             .send(CanvasMsg::WebGL(WebGLCommand::Scissor(x, y, width, height)))
             .unwrap()
@@ -1938,6 +1942,10 @@ impl WebGLRenderingContextMethods for WebGLRenderingContext {
 
     // https://www.khronos.org/registry/webgl/specs/latest/1.0/#5.14.4
     fn Viewport(&self, x: i32, y: i32, width: i32, height: i32) {
+        if width < 0 || height < 0 {
+            return self.webgl_error(InvalidValue)
+        }
+
         self.ipc_renderer
             .send(CanvasMsg::WebGL(WebGLCommand::Viewport(x, y, width, height)))
             .unwrap()