Implement DOM to texture
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This is a prototype of the WebGL DOMToTexture feature. The API should be fine as a privileged extension for now due to security concerns. The working group has been investigating the viability of unprivileged usage but the spec is not ready yet.
Demo video: https://www.youtube.com/watch?v=hpZqEM5hPao
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* Add support for clip masks on text runs.
* Fix atomic ordering of items with multiple shadows.
* Update to bincode + ipc-channel with optimizations.
* Fix some plane splitting precision errors.
* Improve the anti-aliasing quality significantly.
* Add internal ClipChain support.
* Fix diacritic glyphs on Linux.
In addition to the sourceMappingURL comment, there is a second special
comment, "sourceURL", that can be used to set the "display name" of a
style sheet for developer tools. This name is also used as the base
URL for the source-map URL resolution algorithm. sourceURL is
described here:
https://blog.getfirebug.com/2009/08/11/give-your-eval-a-name-with-sourceurl/
The devtools feature bug is here:
https://bugzilla.mozilla.org/show_bug.cgi?id=880831
This patch changes servo to preserve and expose this value for use in M-C.
Now that rust-cssparser reports 1-based locations, bump the required
cssparser version and remove get_location_with_offset. Previously,
some code paths were not calling get_location_with_offset; see
https://bugzilla.mozilla.org/show_bug.cgi?id=1398869 for some
background.
