HTML Canvas: Add the lang IDL attribute to CanvasTextDrawingStyles

[schenney-chromium]

Request for Mozilla Position on an Emerging Web Specification

• Specification title: HTML Canvas
• Specification or proposal URL (if available): Add a lang IDL Attribute to CanvasTextDrawingStyles, and clarify "direction" on same whatwg/html#10873
• Explainer URL (if available):
• Proposal author(s) (@-mention GitHub accounts): @schenney-chromium
• Caniuse.com URL (optional):
• Bugzilla URL (optional):
• Mozillians who can provide input (optional):
• WebKit standards-position: [HTML Canvas] lang IDL attribute for CanvasTextDrawingStyles WebKit/standards-positions#439

Other information

The DOM element, like all DOM elements, accepts a lang attribute that is used to define language specific treatment for font selection (when fonts have locale specific glyphs). Browsers respect this attribute. However, when an OffscreenCanvas is created there is no way to set locale information, possibly resulting in a state where an offscreen canvas produces rendered results that differ from the canvas in which it's output is used. This feature adds a lang IDL attribute to CanvasTextDrawingStyles to give developers direct control over the language for the text drawing and metrics.