send a reply when thread is done exiting
<!-- Please describe your changes on the following line: -->
---
<!-- 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#11467
<!-- Either: -->
- [x] There are tests for these changes OR
- [ ] These changes do not require tests because: in this case if code compiles then it's good enough.
<!-- 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/11497)
<!-- Reviewable:end -->
Changes include:
- Implement file selection and other DOM behaviours in htmlinputelement
- Integrate IpcSender<FileManagerThreadMsg> into ResourceThreads
- Improve filemanager_thread, including adding type_string field to SelectedFile
- Improve interfaces in FileList/File/Blob to accommodate the above changes
Changes include:
- Introduce an IpcSend trait to abstract over a collection of IpcSenders
- Implement ResourceThreads collection to abstract the resource-related
sub threads across the component
- Rename original ResourceThread and ControlMsg into an unifed CoreResource__
to accommodate above changes and avoid confusions
Use constructor pattern instead of separate utility function.
Instead of allowing the Servo HSTS file loading to silently fail, we
should expect that file to always exist and be formatted correctly.
Replace hsts_list, auth_cache, and cookie_jar with http_state
Reverted a few changes
Moved http_state back to factory
Removed unnecessary Arc
Removed Arc for http_state
