Fork of https://rbuckton.github.io/reflect-metadata which works in Firefox. Using reflect-metadata package in a Firefox webextension content script will cause an error on the 4th line of makeExporter "Not allowed to define cross-origin object as property on [Object] or [Array] XrayWrapper". The exception is not displayed by default. You can only see it if you "pause on exceptions" in the debugger.
May not work in node environment.