ESM for browser

[BlackGlory]

Feature Request

The esm files cannot be used in the browser.

as follows:

import('https://unpkg.com/rxjs@6.5.5/_esm5/index.js')
// TypeError: Failed to resolve module specifier "tslib". Relative references must start with either "/", "./", or "../".

import('https://unpkg.com/rxjs@7.0.0-beta.0/dist/esm/index.js')
// TypeError: Failed to resolve module specifier "tslib". Relative references must start with either "/", "./", or "../".

[kwonoj]

#4416