Ensure an error is thrown when attempting to import non-exported bindings.

[jdalton]

For example Canary will throw an error like:

Uncaught SyntaxError: The requested module does not provide an export named 'd'

Safari errors with:

SyntaxError: Importing binding name 'd' is not found.

Firefox Nightly errors with:

SyntaxError: import 'd' not found

Edge (Experimental Flag)

Silent fail (No error message)