api.HTMLCanvasElement.getContext.powerPreference works on macOS only (#9060)
api.HTMLCanvasElement.getContext.powerPreference works on macOS only (#9060)

* api.HTMLCanvasElement.getContext.powerPreference works on macOS only

https://bugzilla.mozilla.org/show_bug.cgi?id=1349799
https://bugzilla.mozilla.org/show_bug.cgi?id=1496459

* Set experimental to true for single implementation
mdn/browser-compat-data,mdn/browser-compat-data,chrisdavidmills/browser-compat-data,chrisdavidmills/browser-compat-data