Auto merge of #21717 - jdm:webgltmp5, r=nox

Make tests for uninitialized renderbuffers pass

- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix #13710
- [x] There are tests for these changes

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components/script/dom/webglframebuffer.rs

@@ -532,6 +532,7 @@ impl WebGLFramebuffer {
 
     pub fn invalidate_renderbuffer(&self, rb: &WebGLRenderbuffer) {
         self.with_matching_renderbuffers(rb, |_att, _| {
+            self.is_initialized.set(false);
             self.update_status();
         });
     }

components/script/dom/webglrenderbuffer.rs

@@ -145,6 +145,7 @@ impl WebGLRenderbuffer {
         };
 
         self.internal_format.set(Some(internal_format));
+        self.is_initialized.set(false);
 
         // FIXME: Invalidate completeness after the call