WebXr: allow for only a single raf message, until callbacks execute
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See https://github.com/servo/webxr/issues/34
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Stylo: replace product={gecko,servo} with engine={gecko,servo-2013,servo-2020}
Renaming the variable helped make sure I looked at every use.
Also auto-generate relevant parts of `CSSStyleDeclaration.webidl`, to make libscript compile accordingly.
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Avoid panic during shutdown when Blobs exist
Observed when closing the UWP app when https://www.joshmatthews.net/demos/lamp.html is the active document.
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Support running WebGL in its own thread or on the main thread.
This is the final missing piece to support WebGL in ANGLE on Windows. ANGLE doesn't support multiple GL contexts on separate threads using the same underlying Direct3d device, so we need to process all GL operations for WebGL on the same thread as the compositor. These changes try to retain enough flexibility to support both approaches so we can get WebGL working on Windows ASAP.
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Changed DOMString usages to string in MediaFragmentParser
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Changed `DOMString` usages to `String`/`&str`.
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update link_called when link function called.
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On call of WebGLProgram::link update link_called to true
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Implement GetElementProperty wd command
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There are a few canvas2d-related dependencies that haven't updated, but they
only use euclid internally so that's not blocking landing the rest of the
changes.
Given the size of this patch, I think it's useful to get this landed as-is.
Media fragment parser
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Media fragment parser for audio and video.
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