What steps will reproduce the problem?

1. Compile this:

import 'dart:collection' as col;

foo(a) {}

main() {
  foo(col).x();
}

What is the expected output?

An error message that:
a. Points to the offending line "foo(col).x();", not the import statement
b. Contains the correct error description, e.g. "library prefix 'col' used as expression"

What do you see instead?

This:

"""
a.dart:1:1: Internal error: unexpected element kind prefix
import 'dart:collection' as col;
^^^^^^
Error: Compilation failed.
"""

What version of the product are you using? On what operating system?

Dart-to-JavaScript compiler (dart2js) version: 0.6.6.0_r25119

Please provide any additional information below.

An alternative fix would be to make libraries true objects that could be passed as values :)