Account for the font of empty input fields
The font of empty fragments is not accounted for in layout. This behavior is incorrect when part of an input field.
- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix#11653
- [X] There are tests for these changes
<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="35" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/11798)
<!-- Reviewable:end -->
Image with height defined in % resizes properly
<!-- Please describe your changes on the following line: -->
Checked the html in the github issue and the image looks like it is resized properly in Servo.
Fixed image resizing when height is specified in percentages.
---
<!-- 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] These changes fix#11723 (github issue number if applicable).
<!-- Either: -->
- [ ] There are tests for these changes OR
- [X] These changes do not require tests because this issue is marked with has-test?
<!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. -->
<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="35" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/11746)
<!-- Reviewable:end -->
Fragment debug_id u16 only exists in debug, prod will format mem address
<!-- Please describe your changes on the following line: -->
Each fragment has a `u16` `debug_id` in debug mode, but no `debug_id` in production to save memory. To format a debug id in production, the address of the empty `debug_id` is displayed.
---
<!-- 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] These changes fix#87 (github issue number if applicable).
<!-- Either: -->
- [X] These changes do not require tests because it looks like it's not possible to mock out `cfg` options in `#[test]`s
<!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. -->
<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="35" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/11442)
<!-- Reviewable:end -->
