Stats

[Rich-Harris]

As mentioned in #1250, it would useful if svelte.compile returned an object that included stats about the component, including things like:

• performance timings
• imports
• used lifecycle hooks
• used components
• declared methods
• expected data properties
• computed properties
• warnings

This would allow us to determine, for example, whether a given Sapper page had any interactivity (if not, no need to serve and run JS to hydrate the page). It would also be relevant to #1102 (whole-app optimisation), though it would take at least two compiler passes unless we also had a svelte.analyse function or something.

Also, it would allow svelte.validate to be removed from the public API, which is good because it currently depends on Stylesheet which is rather awkward.

See also #795.