Auto merge of #21461 - jdm:webgltmp2, r=nox

Various webgl fixes for framebuffer attachment test

These changes resolve all panics on macOS when running framebuffer-object-attachment.html in headless and headful testing.

---
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] There are tests for these changes OR
- [x] Fixes #13710. Fixes #20570.

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1 files changed, 26 insertions, 0 deletions

diff --git a/components/script/dom/webglrenderbuffer.rs b/components/script/dom/webglrenderbuffer.rs
index fa7d7324f94..96ef3bb0d67 100644
--- a/components/script/dom/webglrenderbuffer.rs
+++ b/components/script/dom/webglrenderbuffer.rs
@@ -23,6 +23,7 @@ pub struct WebGLRenderbuffer {
     is_deleted: Cell<bool>,
     size: Cell<Option<(i32, i32)>>,
     internal_format: Cell<Option<u32>>,
+    is_initialized: Cell<bool>,
 }
 
 impl WebGLRenderbuffer {
@@ -34,6 +35,7 @@ impl WebGLRenderbuffer {
             is_deleted: Cell::new(false),
             internal_format: Cell::new(None),
             size: Cell::new(None),
+            is_initialized: Cell::new(false),
         }
     }
 
@@ -66,6 +68,14 @@ impl WebGLRenderbuffer {
         self.internal_format.get().unwrap_or(constants::RGBA4)
     }
 
+    pub fn mark_initialized(&self) {
+        self.is_initialized.set(true);
+    }
+
+    pub fn is_initialized(&self) -> bool {
+        self.is_initialized.get()
+    }
+
     pub fn bind(&self, target: u32) {
         self.ever_bound.set(true);
         self.upcast::<WebGLObject>()
@@ -76,6 +86,22 @@ impl WebGLRenderbuffer {
     pub fn delete(&self) {
         if !self.is_deleted.get() {
             self.is_deleted.set(true);
+
+            /*
+            If a renderbuffer object is deleted while its image is attached to the currently
+            bound framebuffer, then it is as if FramebufferRenderbuffer had been called, with
+            a renderbuffer of 0, for each attachment point to which this image was attached
+            in the currently bound framebuffer.
+            - GLES 2.0, 4.4.3, "Attaching Renderbuffer Images to a Framebuffer"
+             */
+            let currently_bound_framebuffer =
+                self.upcast::<WebGLObject>()
+                    .context()
+                    .bound_framebuffer();
+            if let Some(fb) = currently_bound_framebuffer {
+                fb.detach_renderbuffer(self);
+            }
+
             self.upcast::<WebGLObject>()
                 .context()
                 .send_command(WebGLCommand::DeleteRenderbuffer(self.id));