Auto merge of #18592 - MortimerGoro:dom_texture, r=jdm

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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- [ ] These changes fix #__ (github issue number if applicable).

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components/canvas/Cargo.toml

@@ -21,5 +21,6 @@ ipc-channel = "0.9"
 log = "0.3.5"
 num-traits = "0.1.32"
 offscreen_gl_context = { version = "0.11", features = ["serde", "osmesa"] }
+servo_config = {path = "../config"}
 webrender = {git = "https://github.com/servo/webrender"}
 webrender_api = {git = "https://github.com/servo/webrender", features = ["ipc"]}