Changes in 20210101210516

Built from cdd65df84242fa01e9b2c690fb9078d7fba46cb6

..index..
Bug 1627014 R[Core:Canvas: 2D]Implement `CanvasRenderingContext2D.createConicGradient`
Bug 1684571 R[Core:GFX: Color Management]Don't allow unused mut.
Bug 1684599 R[Core:GFX: Color Management]Make iccv4 support default value a feature
Bug 1678047 R[Core:Layout]Perma [tier2] TEST-UNEXPECTED-PASS | bugs/456219-1c.html == bugs/456219-1-ref.html | image comparison, max difference: 60, number of differing pixels: 499
Bug 1676966 R[Core:Layout: Text and Fonts]Fenix takes longer to reflow wikipedia.org than Fennec, partially due to font initialization
Bug 1684567 R[Core:SVG]unspecified dimension of image tag is rounded to integer
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Changes to 6 bugs - 6 fixed.