Request for Mozilla Position on an Emerging Web Specification

• Specification Title: CSS Houdini family features (Paint API, Typed OM, Layout API etc.)
• Specification or proposal URL: CSS Painting API Level 1
• Caniuse.com URL (optional):
• Bugzilla URL (optional): https://bugzilla.mozilla.org/show_bug.cgi?id=1302328
• Mozillians who can provide input (optional): @tantek, Andrew Overholt

Other information

• Intent to Experiment: CSS Houdini Paint API Level 1
• CSS/Houdini - Mozilla Wiki
• META Implement Houdini CSS Painting API Level 1 spec
• META Implement Houdini CSS Layout API Level 1 spec
• META implement Houdini CSS Properties and Values API
• META Implement CSS Houdini "Worklets Level 1" spec
• Houdini "Worklets Level 1" prototype implementation
• Is Houdini ready yet?

Under consideration: Worklets Level 1, CSS Paint API Level 1, CSS Layout API Level 1
Currently being implemented: CSS Typed OM Level 1, CSS Properties and Values API Level 1
— according to the Mozilla Wiki on DOM/Houdini

“Worklets is one of the Houdini specs we are "considering" but have no firm implementation plans for. Unlikely for 2018, we can reconsider when doing 2019 CSS priorities.”
— Tantek Çelik, bugzilla bug #1315239

With Chrome's shipped Paint API and partial implementations of other APIs, coupled various, spec-compliant polyfills appearing developer interest seems to be on the rise, with almost all JavaScript/Web-related conferences sporting a talk on the lineup about the magical developer-facing features, and encouraging the audience to start experimenting. Browser support, of course, always comes up (and never fails to chill the excitement of the talk presented), and although @surma's implementation tracker does a good job in summarizing the (current and expected) support of various browsers, a clear cut decision/expectation on various parts of the Houdini family features would be still very useful.