* 'master' of https://github.com/sveltejs/svelte: (137 commits)
  -> v3.19.2
  fix lazy code breaks in build
  fit bitmask overflow initial dirty value in 'if' blocks (sveltejs#4507)
  add dev runtime warning for unknown slot names (sveltejs#4501)
  fix render fallback slot content due to whitespace (sveltejs#4500)
  docs: describe falsy and nullish attribute behavior (sveltejs#4498)
  in spread, distinguish never-updating and always-updating props (sveltejs#4487)
  chore: more specific typings, and add README note about Yarn (sveltejs#4483)
  update changelog
  check for unknown props even if component doesn't have writable props (sveltejs#4454)
  Bump codecov from 3.5.0 to 3.6.5 (sveltejs#4433)
  fix bitmask overflow for slot (sveltejs#4485)
  mark module variables as mutated or reassigned (sveltejs#4469)
  docs: referenced_from_script var value (sveltejs#4486)
  docs: clarify default prop behaviour (sveltejs#4460)
  site: turn fancybutton into custombutton (sveltejs#4476)
  update changelog
  exclude global variables from $capture_state (sveltejs#4475)
  -> v3.19.1
  don't treat $$-names as stores during invalidation (sveltejs#4453)
  ...