What I think is that what should be needing for browser extensions is to be able to write extensions in C, and available only for manual install by advanced users (so that it is not available to the official catalog of extensions).<p>However, additional capabilities to interact with the browser are also needed, including to implement new and intercept existing: protocols, MIME types, character encodings, HTML commands, CSS commands, JavaScripts in web pages (and the API they have access to), ARIA, menus, user interface elements, etc. (I think things will need to be rewritten to make this work efficiently, including moving many features to extensions which are then included by default, instead of being core features.)<p>Making C APIs for purposes would be helpful, although even if the existing API are with JavaScripts, JavaScript functions can be accessed by C codes by implementing N-API, I suppose.