Removed integrity check and test for no-cors requests
Removed Step 30.2 which raised a JS TypeError if the integrity metadata was not empty. I manually ran `new Request("", {"mode" : "no-cors", "integrity" : "not an empty string"});` in servo to validate that the exception no longer arose.
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- [x] These changes fix#18345
- [x] These changes do not require tests because according to the ticket "Unfortunately, there's no automated test available for this yet because we are having trouble updating our copy of the upstream tests. "
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Land the test cases that should've landed with the selectors update
PR for #15448
- Added test for pseudo-element with whitespace #15335
- Added tests for empty values in `[att^=""]`, `[att$=""]` and `[att*=""]` selectors #15394 (tests for `[att~=""]` have been added with #15440)
- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix#15448
- [X] There are tests for these changes
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TEST: fix and add case of po-observe.any.js
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1. implementing step 3 from the [`PerformanceObserver.observe()`](https://w3c.github.io/performance-timeline/#dom-performanceobserver-observe()) method spec properly.
2. also add cases about step 1 & 2
work on the top of #18283
r? @ferjm
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"javascript:" urls: execute in correct global scope
<!-- Please describe your changes on the following line: -->
#### Summary
This pull request makes `javascript:` urls execute in the correct global scope.
#### Example
```html
<script> var x = 4; </script>
<!-- this branch: logs "4" -->
<!-- master: undefined variable error -->
<a href="javascript:console.log(x)">link</a>
```
#### Questions
I'm new to servo and rust, so I'm unsure about these changes. In particular:
* What's the appropriate place to evaluate the js?
* I moved it to `handle_navigate`, but I'm not sure if this will catch all occurrences of `javascript:` urls. I also don't know if this will execute in the correct thread and the correct window.
* What should I do with the result of the js evaluation?
* I just ignored it. The previous behavior displayed it as the content of a new page load.
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- [x] These changes fix#15147, #16718
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