| <!DOCTYPE html> | |
| <script> | |
| function createMutationObserver(FunctionConstructor = Function) { | |
| const mutationObserver = new parent.MutationObserver(new FunctionConstructor(` | |
| this.callbackInvocations++; | |
| `)); | |
| mutationObserver.callbackInvocations = 0; | |
| mutationObserver.observe(parent.mutationObserverTestRoot, { childList: true }); | |
| return mutationObserver; | |
| } | |
| </script> |