Implement matchMedia and MediaQueryList
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Fixes#13376.
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Disable EventSource until it is fully implemented.
This also causes a number of tests that currently time out to fail quickly.
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Implement promise bindings
This implements support for using Promises in WebIDL, executing promise callbacks in batches (equivalent to running all enqueued jobs from a setTimeout(0)), and attaching native callbacks to promise objects. This is the combined work of myself, @dati91, and @mmatyas based on the following prior work in Gecko:
* Codegen.py
* Promise.webidl
* Promise.cpp/Promise.h
* PromiseNativeHandler.h
This does not implement microtasks per #4283. This allows us to make progress on testing code that requires the use of Promises right now; the microtasks work is more complicated, but also largely orthogonal to implement.
Requires https://github.com/servo/mozjs/pull/89, https://github.com/servo/rust-mozjs/pull/287, and https://github.com/servo/rust-mozjs/pull/294.
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Put back video metadata
I updated the `video-metadata-rs` crate: now, no more ffmpeg, just pure rust. The webm format isn't checked yet.
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Implemented Navigator.cookieEnabled
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Implement HTMLDataElement#value
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Implement HTMLDataElement#value
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Implements HTMLDialogElement#close
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Implements HTMLDialogElement#close according to [link](https://html.spec.whatwg.org/multipage/#the-dialog-element:dom-dialog-close)
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disable browsing context name test
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When loading HTTP requests, initialise the request ID only if devtools
are used, to lessen the pressure put on the RNG initialisation.
This tentatively fixes#11100 on OS X.
