Auto merge of #20674 - simartin:issue_20556, r=nox

Issue #20556: Implement proper checks in WebGLRenderingContext's bindBuffer()

Implement missing check, about deleted buffers.
---
- [X] `./mach build -d` does not report any errors
- [X] `./mach build-geckolib` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #20556
- [X] There are tests for these changes

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components/script/dom/webglbuffer.rs

@@ -77,6 +77,9 @@ impl WebGLBuffer {
 
     // NB: Only valid buffer targets come here
     pub fn bind(&self, target: u32) -> WebGLResult<()> {
+        if self.is_deleted() || self.is_pending_delete() {
+            return Err(WebGLError::InvalidOperation);
+        }
         if let Some(previous_target) = self.target.get() {
             if target != previous_target {
                 return Err(WebGLError::InvalidOperation);
@@ -141,6 +144,10 @@ impl WebGLBuffer {
         self.pending_delete.set(true);
     }
 
+    pub fn is_pending_delete(&self) -> bool {
+        self.pending_delete.get()
+    }
+
     pub fn add_vao_reference(&self, id: WebGLVertexArrayId) {
         let mut vao_refs = self.vao_references.borrow_mut();
         if let Some(ref mut vao_refs) = *vao_refs {