Remember that Mozilla is making a mobile OS based on Firefox, where all apps are written in HTML/JS. As part of this, they're adding API's to provide the sort

Remember that Mozilla is making a mobile OS based on Firefox, where all apps are written in HTML/JS. As part of this, they're adding API's to provide the sort of hooks that mobile apps need, such as being aware of battery status. They would also like these to be standardized across all browsers, so that HTML apps can properly compete with "native" apps.