Intent to prototype: Import maps

[Yoshi Cheng-Hao Huang]

Summary:

Import maps allow control over what URLs get fetched by JavaScript import statements and import() expressions.

Bug:

https://bugzilla.mozilla.org/show_bug.cgi?id=1688879

Standards body:

https://wicg.github.io/import-maps/

Link to standards positions:

https://mozilla.github.io/standards-positions/#import-maps

Platform coverage:

All

Preference:

dom.importMaps.enabled, currently disabled by default.

Other browsers:

Chrome has shipped it since 89

https://chromestatus.com/feature/5315286962012160

Web-platform-tests:

https://github.com/web-platform-tests/wpt/tree/master/import-maps