<!-- Please describe your changes on the following line: --> Got `window.top` and `window.parent` to return the right result inside a `mozbrowser` iframe. --- <!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: --> - [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 <!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. --> Source-Repo: https://github.com/servo/servo Source-Revision: 280bfc961a013bec58ba23d756db002b3e44fdef