Use specific assertions
Similar to #19865
r? jdm
Note: Should I squash all the commits into one commit?
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- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes do not require tests because it should not break anything
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Implement the create an element for token algorithm
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<!-- 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#19392 and fix#19393 (github issue number if applicable).
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- [ ] There are tests for these changes OR
- [ ] These changes do not require tests because _____
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implement valid DatetimeLocal input
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implement valid Date time Local input
part of #19172
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<!-- 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#19587 fix #19603(github issue number if applicable).
<!-- Either: -->
- [ ] There are tests for these changes OR
- [ ] These changes do not require tests because _____
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This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/19602)
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