Issue 21810/improve validation methods
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This is a start at addressing #21810. I'm putting these changes out early to get some feedback on the following items:
1. I added unit tests for the validation methods mentioned in #21810, because I couldn't tell whether any of the existing WPT tests covered them. Are these tests worthwhile? Are any of them unnecessary?
2. I changed the implementation for `is_valid_floating_point_number_string` so that it passed the tests. The previous version of the function wasn't restrictive enough (it allowed certain whitespace characters before the number string).
3. I changed the catch-all condition in `htmlinputelement.rs` to account for the remaining input types that don't have a value sanitization algorithm. This last change seems good to me since we won't be able to add a new input type without adding it to the case and checking the spec for an algorithm.
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- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix#21810
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Media fragment parser
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Media fragment parser for audio and video.
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- [X] These changes fix#22366 (GitHub issue number if applicable)
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- [X] There are tests for these changes OR
- [ ] These changes do not require tests because ___
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Clean-up navigation
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1. Navigation as a result of following a hyperlink should be done in a task: https://html.spec.whatwg.org/multipage/links.html#following-hyperlinks:dom-manipulation-task-source
2. The javascript url navigation should also be done in a task: https://html.spec.whatwg.org/multipage/browsing-the-web.html#navigating-across-documents:dom-manipulation-task-source
3. In `window.load_url`, it seems there is no need to send a message to the script-thread(the entirety of `load_url` should instead be done in a task when appropriate), so we can just do that last part "sync" by calling a method on the script, which will send a message to the constellation(for the parallel navigation steps), or queue task(for the JS navigation), as appropriate.
4. Separate the "normal" navigation flow from the handling of "navigate an iframe" message from constellation, since doing everything in one method as was previously done with `handle_navigate`, is confusing.
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- [ ] These changes fix #___ (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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