Simplify gl.getShaderParameter() (fixes #20562)

The expectation change is due to the shader now using its DOM-side compile status.
It is actually a bug for the shader to think it actually compiled successfully,
but at least it does so consistently now.

components/script/dom/webglshader.rs

@@ -192,6 +192,10 @@ impl WebGLShader {
         }
     }
 
+    pub fn is_marked_for_deletion(&self) -> bool {
+        self.marked_for_deletion.get()
+    }
+
     pub fn is_deleted(&self) -> bool {
         self.marked_for_deletion.get() && !self.is_attached()
     }