Flow Files

Likely to cause new Flow errors: * flow will now validate variance in interface declarations * Bad cyclic object types are now banned. e.g. type O_loop = { p: 0, __proto__: O_loop } will cause an error. * Flow is now stricter with generic mapped type. example

Notable bug fixes: * We improved the refinement system of match. Some code that previously gets a general type will now get a refined type. example * allow opaque types to be used as keys to computed object properties * autocomplete on import { | } from 'a'; will only suggest values, not types. * flow-dev-tools now properly detects unused suppressions

IDE: * Flow now provide auto-import code actions for all unbound names, even through they might resolve to a global. It can be helpful when the global is not what you want.

Library Definitions: * Add bigint functions to DataView